Heart breaker, thumb sucker!

Samuel has started sucking his thumb. Should I be worried? I try to pull it out whenever I can, but I can't be there all the time. Is this something kids grow out of? Sigh. I must sound like an overly worried mom. I just don't want him doing it when he is in kindergarten. Anyway, this cutie has started sleeping from about 9:30-10:00 pm until 8:00 am. It is wonderful. He is a good kid. Here are a few pictures from the past week. We love you all.