Just out of curiosity, if you haven't logged on your BTC client 3 months in and received a payment a week after you stopped using the client.
Wouldn't it be possible that if we didnt download the full blockchain the client's wallet wouldnt be updated properly?
Sure. The wallet will be updated when it reaches that part of the blockchain. However that doesn't change that your balance is there, even if your wallet doesn't reflect it. You just need to give it time. You would still be able to check your balance with blockexplorer.com , for instance.