Lots of horses seem to do this! I know quite a few with wonky mouths.
My friends 6 month old colt damaged his facial nerves quite badly, his lower lip would hang (like he was sleeping) constantly and his top was twisted right over. He was a well bred sec D bought with showing in mind, so she was a bit gutted, however by the time he was a yearling, you wouldn't be able to tell he'd done anything!
It never affected him though, drinking and eating, obviously he was never ridden though!
She had an accident in the field yesturday and has damaged the nerve. She has also shredded both sides of her face and her stifle. The vet said that it might heal and go back to normal so fingers crossed, it is a relief to hear that Rafi is still going well!