My DS was accelerated this year and we have some of the same concerns
We do not want to punish him for being his age, but the sometimes silly behaviour may be becoming an issue, and the teacher is concerned this age gap may increase as time progresses.
I'm no expert, but I would think that the gap would close as all of the children get older. One thing I've noticed with DSs friends that are a year older is that they can be just as silly as DS. They may not show those behaviors as frequently as DS or may have a better social awareness of when to be silly, but DS isn't the only silly one.
We try to encourage DS to pay attention to who's around and to observe the behaviors of others - ie. if no one's laughing, they probably don't find whatever he's doing/saying funny. Sometimes, we think DS is hilarious when he's being silly, but we have to remind him that just because we do, not everyone else will think so. It's difficult to encourage DS to be himself, but also be mindful of what others may be thinking - only because we want him to fit in OK and have friends.
Good luck.
