Recently we sharded few big collections in our database (2.2.0-rc1)

First collection was balanced just fine:
oggiReporting.site.mainStats chunks:
RS02 238
RS03 238
RS01 239

But for second collection we get a balancer error in mongos log every few seconds:

Fri Aug 17 00:56:27 [Balancer] ns: oggiReporting.playlist.mainStats going to move { _id: "oggiReporting.playlist.mainStats-campaignId_MinKeyplaylistId_MinKeydate_MinKey", lastmod: Timestamp 1000|0, lastmodEpoch: ObjectId('502be6c21d848a61a13d51eb'), ns: "oggiReporting.playlist.mainStats", min:

{ campaignId: MinKey, playlistId: MinKey, date: MinKey }

, max:

{ campaignId: "014869ee-5d62-4212-a609-40edcc2169d3", playlistId: "0c5bb01a-5780-413d-8d7c-b22c722e6ad4", date: new Date(1309309200000) }

, shard: "RS01" } from: RS01 to: RS02 tag []
foo:

{ campaignId: "0095af50-203b-4e1a-9337-6dad60a46688", playlistId: "09038ddd-ac89-4818-b6c3-90c3c43cdce9", domain: "biography.com", date: new Date(1311120000000), partition: "2011-07" }

*c: ns:oggiReporting.domain.mainStats at: RS02:RS02/RPTDB-RS02-Zuse1b-S01.oggifinogi.com:27018,RPTDB-RS02-Zuse1c-S01.oggifinogi.com:27018,RPTDB-RS02-Zuse1d-S01.oggifinogi.com:27018 lastmod: 2|0||000000000000000000000000 min:

{ campaignId: MinKey, playlistId: MinKey, domain: MinKey, date: MinKey }

max:

{ campaignId: "0095af50-203b-4e1a-9337-6dad60a46688", playlistId: "09038ddd-ac89-4818-b6c3-90c3c43cdce9", domain: "biography.com", date: new Date(1311120000000), partition: "2011-07" }

key:

{ campaignId: "0095af50-203b-4e1a-9337-6dad60a46688", playlistId: "09038ddd-ac89-4818-b6c3-90c3c43cdce9", domain: "biography.com", date: new Date(1311120000000) }

Fri Aug 17 00:56:27 [Balancer] Assertion: 13141:Chunk map pointed to incorrect chunk
0x5389f1 0x6ed1cb 0x57d090 0x5312ec 0x532d66 0x670b9e 0x6724e4 0x72ab79 0x7f4a00f4cd8c 0x7f4a002eec2d
/usr/bin/mongos(_ZN5mongo15printStackTraceERSo+0x21) [0x5389f1]
/usr/bin/mongos(_ZN5mongo11msgassertedEiPKc+0x9b) [0x6ed1cb]
/usr/bin/mongos(_ZNK5mongo12ChunkManager9findChunkERKNS_7BSONObjE+0x540) [0x57d090]
/usr/bin/mongos(_ZN5mongo8Balancer11_moveChunksEPKSt6vectorIN5boost10shared_ptrINS_11MigrateInfoEEESaIS5_EEb+0x5ac) [0x5312ec]
/usr/bin/mongos(_ZN5mongo8Balancer3runEv+0x986) [0x532d66]
/usr/bin/mongos(_ZN5mongo13BackgroundJob7jobBodyEN5boost10shared_ptrINS0_9JobStatusEEE+0xbe) [0x670b9e]
/usr/bin/mongos(_ZN5boost6detail11thread_dataINS_3_bi6bind_tIvNS_4_mfi3mf1IvN5mongo13BackgroundJobENS_10shared_ptrINS7_9JobStatusEEEEENS2_5list2INS2_5valueIPS7_EENSD_ISA_EEEEEEE3runEv+0x74) [0x6724e4]
/usr/bin/mongos() [0x72ab79]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x6d8c) [0x7f4a00f4cd8c]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d) [0x7f4a002eec2d]
Fri Aug 17 00:56:27 [Balancer] distributed lock 'balancer/RPTSRVC-Zuse1b-S01.oggifinogi.com:27017:1345162100:1804289383' unlocked.
Fri Aug 17 00:56:27 [Balancer] scoped connection to RPTDB-CFG-Zuse1b-S01.oggifinogi.com:27019,RPTDB-CFG-Zuse1c-S01.oggifinogi.com:27019,RPTDB-CFG-Zuse1d-S01.oggifinogi.com:27019 not being returned to the pool
Fri Aug 17 00:56:27 [Balancer] caught exception while doing balance: Chunk map pointed to incorrect chunk

I tried to reboot mongos as well as config and replica set servers - no luck