Could my son be understanding that hes gonna have a sibling soon or is he just understanding how to give affec?

affection?? my son has been really showing alot of affection lately. he just hugs me alot and tells me he loves me, or he gets in the bed with me just to snuggle. hes 3 btw he would tell me he loves me but only when I say it first. but now hes like extremely affectionate. but I dont know if hes doing it because hes understanding that a new baby is coming or could he just be leaning how to give affection?