Warnings in Standby Logs

Hi,

I'm on 9.1.2 and occasionally get what are probably harmless warning messages in my logs, but because I have the responsibility of
ensuring we haven't lost a bit of data between our master and standby, I feel I should know exactly what they mean. I occasionally
see "invalid record length" and "record with zero length" in my logs, and they almost only occur during reboots (the "consistent
recovery state reached" message gives me the warm-fuzzy, but then when they're followed by either of those two, it leaves me
wondering). For example, I had to reboot my hot standby twice this month:

2012-03-16 10:23:28 CDT LOG: received smart shutdown request
2012-03-16 10:23:28 CDT FATAL: terminating walreceiver process due to administrator command
2012-03-16 10:27:33 CDT LOG: database system was interrupted while in recovery at log time 2012-03-16 10:14:15 CDT
2012-03-16 10:27:33 CDT HINT: If this has occurred more than once some data might be corrupted and you might need to choose an
earlier recovery target.
2012-03-16 10:27:33 CDT LOG: entering standby mode
2012-03-16 10:27:34 CDT LOG: redo starts at 9/B98D6968
2012-03-16 10:27:34 CDT LOG: consistent recovery state reached at 9/B9F171B0
2012-03-16 10:27:34 CDT LOG: database system is ready to accept read only connections
2012-03-16 10:27:34 CDT LOG: invalid record length at 9/B9F85E78
2012-03-16 10:27:34 CDT LOG: streaming replication successfully connected to primary
2012-03-16 10:28:07 CDT LOG: received smart shutdown request
2012-03-16 10:28:07 CDT FATAL: terminating walreceiver process due to administrator command
2012-03-16 10:28:07 CDT LOG: shutting down
2012-03-16 10:47:00 CDT LOG: database system was interrupted while in recovery at log time 2012-03-16 10:14:15 CDT
2012-03-16 10:47:00 CDT HINT: If this has occurred more than once some data might be corrupted and you might need to choose an
earlier recovery target.
2012-03-16 10:47:00 CDT LOG: entering standby mode
2012-03-16 10:47:01 CDT LOG: redo starts at 9/B98D6968
2012-03-16 10:47:02 CDT LOG: consistent recovery state reached at 9/BA2D3490
2012-03-16 10:47:02 CDT LOG: database system is ready to accept read only connections
2012-03-16 10:47:02 CDT LOG: invalid record length at 9/BA2D3490
2012-03-16 10:47:02 CDT LOG: streaming replication successfully connected to primary

Is this something I should be concerned about (and even if not, where can I read about what these mean in detail)?

Also, is there a more elegant shutdown command I can use so that when it starts up again, I don't get these "invalid record length"
type messages?

P.S. I have searched the forums and the docs several times, so I apologize if I missed the answer/tutorial on this somewhere.

Thanks,

Eric Simon