we worried about this, too, when DD (now nearly 6) was this age. toys held about one second of interest for her, and all she wanted to do was go on walk after walk and get her billions of questions answered.
she plays more now than she did then, but even now, there's always something a bit off about it - the stories she makes up to go with Lego structures are pretty weird and often her drawings are more scientific than creative, etc. she's super-happy, though, these days, so mostly i've stopped wondering what's up!
