Was the wind down the runway or slightly off? If you were crabbing or using wing down until the flare than that may explain it. Or it could be as simple as where you were looking or even if you were trying to account for sitting on the left and aiming slightly left?
I wouldn't be surprised if your next lesson is fine and you never know why it happened! Little things like this will still occur even after you get your license, so don't worry too much about it as long as it's safe(-ish!).
EDIT: Light winds can be fairly variable. Are there obstacles like trees along the runway? There are some places I've been to that you will suddenly get a blast of wind between a gap in the trees. It doesn't need to be much to upset your approach.
Last edited by The500man; 17th July 2012 at 14:29.