Subconscious siblings

So, I just found out last week that I was pregnant, and lately my son who's 9 has been very clingy, which he never really was. He's always been a very independent little boy for as long as I can remember. Is it possible that he could possibly know somethings up? My boyfriends 8 yr old is the same way, he's been extra clingy and we haven't told them anything yet. I just thought it was odd...