My LO is 8 months old. He has refused a pacifier since he was 2 months old and just liked to chew on his toys. Recently, he's started to "chew" on his thumb - is this the start of a thumb sucker? He doesn't fall asleep with it in his mouth or do it constantly, just when he is tired or upset.

I was a thumb sucker until past age 2 and weaned off it just fine, so I'm not really worried about it, just curious what others experience has been.