not my 7yo, I hasten to add..
DS was bitten by one of his classmates at a party over the holidays. No mark, no long-term consequences, but my DM had me thinking as she said that when she ran a playgroup (granted, this was 20 years ago) they were told to report persistent biting as it was seen as a sign of possible abuse.
Now IMHO most children bite once or twice as toddlers - but I know this child has bitten others at school, and hes 7, FFS.
How worried would you be? Enough to report it (to someone other than the child's mother - DS did that at the time, and she doesn't really care)? I am dithering....