Yes, it may be because they hear so many people , teachers & kids, talking around them and they are likely to pick up words easily and faster. But that doesn't mean a child will lag behind .....he will surely learn to speak... sooner or later. not an issue. He has already started and so he'll catch up soon. Let him take his own time.
Both my kids learnt to talk late. But once they started , there was no stopping them.And sometimes I have to tell them to be quiet and let me have some peace.
Enjoy a little peace while you can.:)
Cheers,
Sonalika