Another Thumb Sucker?

What is it with my kids and their thumbs. So I worked and worked and worked with little Anna to love her binki. I tried ALL kinds and finally she took the NUK. She didn't suck on it all day but when she was fussy I would put it in and it would soothe her for a bit. Well, that is the end of the NUK's. One day I walked in on her and she was full on sucking her thumb. I couldn't believe my eyes. Why did it take her four months to find it? Now she is truly a sucker, but only does it when she is going to sleep and has her little blankie in her hand (just like Luke and Ruby) except when I caught her during her rice cereal feeding. I suppose the good thing about it is I don't have to carry those silly binki's around anymore and always wonder where they are... however, the time will come when I am wondering how to stop her from this horrible habit. From experience though, thumb suckers know how to pacify themselves when they need it since it is always attached to them.
Oh Anna, you look so cute with your thumb in your mouth!!