When you upgrade from 2.2.2 to 2.2.4 or 2.4.3, the init scripts are overwritten in /etc/init.d/mongod. Some people set options in here like the replset and --shardsvr or --cfgsvr with puppet like us. During an upgrade if mongod is started before puppet pushes the right config (or people who don't use puppet and lost their config you overwrote) the mongod will not know what it should be doing like being a config server or being part of a replset.