2 shards, each one is a replica set with 3 machines.
shards are named shard1 and shard2
shard1 consists of cs-mongodb01

{d|g|f} machines,
shard2 consists of cs-mongodb02{d|g|f}

machines.

there are plenty of following logs on shard2 machines:
Tue Jan 29 07:15:54 [ReplicaSetMonitorWatcher] dbclient_rs nodes[2].ok = true cs-mongodb01g.load.net:27017
Tue Jan 29 07:15:54 [ReplicaSetMonitorWatcher] dbclient_rs nodes[0].ok = true cs-mongodb01d.load.net:27017
Tue Jan 29 07:15:54 [ReplicaSetMonitorWatcher] dbclient_rs nodes[1].ok = true cs-mongodb01f.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] checking replica set: shard1
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] ReplicaSetMonitor::_checkConnection: cs-mongodb01g.load.net:27017

{ setName: "shard1", ismaster: true, secondary: false, hosts: [ "cs-mongodb01g.load.net:27017", "cs-mongodb01f.load.net:27017", "cs-mongodb01d.load.net:27017" ], primary: "cs-mongodb01g.load.net:27017", me: "cs-mongodb01g.load.net:27017", maxBsonObjectSize: 16777216, localTime: new Date(1359429364931), ok: 1.0 }

Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[2].ok = true cs-mongodb01g.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[0].ok = true cs-mongodb01d.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[1].ok = true cs-mongodb01f.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] _check : shard1/cs-mongodb01d.load.net:27017,cs-mongodb01f.load.net:27017,cs-mongodb01g.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] ReplicaSetMonitor::_checkConnection: cs-mongodb01d.load.net:27017

{ setName: "shard1", ismaster: false, secondary: true, hosts: [ "cs-mongodb01d.load.net:27017", "cs-mongodb01f.load.net:27017", "cs-mongodb01g.load.net:27017" ], primary: "cs-mongodb01g.load.net:27017", me: "cs-mongodb01d.load.net:27017", maxBsonObjectSize: 16777216, localTime: new Date(1359429364932), ok: 1.0 }

Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[2].ok = true cs-mongodb01g.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[0].ok = true cs-mongodb01d.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[1].ok = true cs-mongodb01f.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] ReplicaSetMonitor::_checkConnection: cs-mongodb01g.load.net:27017

{ setName: "shard1", ismaster: true, secondary: false, hosts: [ "cs-mongodb01g.load.net:27017", "cs-mongodb01f.load.net:27017", "cs-mongodb01d.load.net:27017" ], primary: "cs-mongodb01g.load.net:27017", me: "cs-mongodb01g.load.net:27017", maxBsonObjectSize: 16777216, localTime: new Date(1359429364934), ok: 1.0 }

Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[2].ok = true cs-mongodb01g.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[0].ok = true cs-mongodb01d.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[1].ok = true cs-mongodb01f.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] ReplicaSetMonitor::_checkConnection: cs-mongodb01f.load.net:27017

{ setName: "shard1", ismaster: false, secondary: true, hosts: [ "cs-mongodb01f.load.net:27017", "cs-mongodb01d.load.net:27017", "cs-mongodb01g.load.net:27017" ], primary: "cs-mongodb01g.load.net:27017", me: "cs-mongodb01f.load.net:27017", maxBsonObjectSize: 16777216, localTime: new Date(1359429364935), ok: 1.0 }

Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[2].ok = true cs-mongodb01g.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[0].ok = true cs-mongodb01d.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[1].ok = true cs-mongodb01f.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] ReplicaSetMonitor::_checkConnection: cs-mongodb01g.load.net:27017

{ setName: "shard1", ismaster: true, secondary: false, hosts: [ "cs-mongodb01g.load.net:27017", "cs-mongodb01f.load.net:27017", "cs-mongodb01d.load.net:27017" ], primary: "cs-mongodb01g.load.net:27017", me: "cs-mongodb01g.load.net:27017", maxBsonObjectSize: 16777216, localTime: new Date(1359429364968), ok: 1.0 }

Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[2].ok = true cs-mongodb01g.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[0].ok = true cs-mongodb01d.load.net:27017
Tue Jan 29 07:16:04 [ReplicaSetMonitorWatcher] dbclient_rs nodes[1].ok = true cs-mongodb01f.load.net:27017

Why mongod is trying to check another replica's instances? Is it ok?
I thought, that information about shards is stored only on config servers, and mongod instances knows nothing about them.