Strange, I am seeing the same thing. I have a new transaction that already has 4 confirmations, but the prior transaction - over 2 hours ago, still has zero. Unfortunately the one with zero confirmations is .11 BTC, almost
Different transactions have different priority.
https://en.bitcoin.it/wiki/Transaction_fees If it is on blockchain there's nothing to fear (if i'm wrong please someone correct me) :-p just sit back, relax, and wait ;-)