restored wallet from backup - times differ

[CloudySkies]

I recently restore my wallet.dat from a backup since my current one appeared to be corrupted (or at least, it kept causing Bitcoin-Qt to crash).  That worked, and all my Bitcoins are still there, phew!
One thing I noticed though is that the transaction times are slightly different, usually a few minutes later than in my original wallet.  Can anyone tell me why?  I'm assuming it's something to do with the way the Blockchain works, but I couldn't find any info on this.
Thanks in advance...

[Foxpup]

The wallet.dat file stores (among other metadata) the actual time each transaction was made, and this metadata will naturally not be present for transactions made after the backup (discovered during a rescan of the blockchain). For such transactions, the time displayed will be the timestamp of the block it was included in, which will generally be several minutes later.

[CloudySkies]

That makes total sense.  Thanks for the explanation, Foxpup!