Anterior itself is not a problem its if its low lying at all it can cause proplems, though they would have told you if it was also low. mines anterior and they didnt mention it to me, i looked it up when i got home!
did find a chart somewhere that explainded them all, with terminology but cant find it now, but it just tells you where its fixed onto your womb, anterior = front, posterior = back, and then got a name for each side and all can be praevia (low lying)
so nothing to worry about! hope that helps!!!