So thats frustrating went invalid even tho we have a 30 sec faster timestamp then BTC guild on block 322930
Timestamp is set by the mining pool when it is generating the work. It doesn't even remotely have to be the actual time, it can be up to 10 minutes ago or 2 hours into the future and will still be accepted as a block.
It can also mean both times are exact but slush had network issues and reported it 31s late which has happened quite often in the past...