Shelf above crib?

tkhrabs313

Hey ladies!

My MIL made the cutest fabric blocks that match the nursery to spell out Dominic's name.  I was originally going to do the wooden letters above his crib, but now that I have these blocks, I was thinking of putting a shelf above the crib and putting the blocks there. 

 So, my question is...is it a bad (safety-wise) to put a lightweight shelf above the crib?