My 10 year old son has larger than normal breasts... not very conspicuous... is this normal for his age? should i be worried?

Depends on situation: As many as 1/2 of males experience transient breast enlargement in puberty which generally fades in a year or less. At 10, its a bit early for that process.Overweight males tend to have fat accumulations that appear as breast enlargement & these persist as long as they are overweight. There are some other rare causes & a visit with the kids doc can sort out the problem.