Actually I'd say this hints at a serious bug in the client. Look at the record of Ronald's address for receiving money from the mining pool:http://blockexplorer.com/address/1D3hzQnKeQuKoHZ7vZPu8bygiRRMvfhSow
He receives payments and then sends them on, returning again and again to a zero balance.
Until the first tx of 2011-01-30, when he receives 3.37. From then on, he no longer reduces his balance to zero; he reduces it to 3.37. This transaction alone is not transferred.
Clearly the wallet simply missed this transaction. Yet it picked up a transaction to the same address 8 hours earlier and one two hours later.
So there are two possibilities that I see. One, Ronald was messing with his wallet at that time and somehow removed this address from the wallet for a brief time, then put it back. Not an easy thing to do, I don't think. (Maybe deleting the wallet for a while, then restoring it?)
Possibility two is that the client somehow overlooked the transaction due to a bug. Obviously not something that happens very often. What could it be? Maybe something to do with block collisions and chain reorg?
The block with the missed transaction was 105286. Any way to tell at this late date whether there was anything unusual about this block?