Common. The tonsils ; adenoids in kids grow faster in early ; middle childhood than other body parts. At 6-9 kids often snore. At this point the glandular tissue stabalizes its size but the kids continue to grow. By the mid teens the snoring has gone. Snoring in 3-4 yo or assoc excessive day sleeping needs an evaluation for sleep apnea.
Get it treated NOW. Recent documentation has shown that children who snore may also have breathing and sleep issues that can effect behavior, and school performance. Don't wait get your child evaluated/treated ASAP. Thanks, for caring to ask for your child! -)