DS2 will be 3 in September. Over the last month or so, while we've been struggling with getting DS1 to stop thumb sucking, DS2 has decided that sucking his thumb is funny. He puts his thumb in his mouth and then peers at me, waiting for me to react. Could he end up actually sucking his thumb from this? Should I just ignore him? He's never been a 'sucky' baby, so I don't think he could be a real thumb sucker, but still ...