My ds has also been checking them out the last couple of weeks. He reaches up and tries to turn the knob (a month or so ago he learned how to twist things and so now he's really into knobs and such). Taking them off (if they do come off) is a great idea. At this point, when I tell him not to touch them, he just looks at them and leaves them alone but I'll resort to taking them off if I need to eventually.