I'd carefully evaluate everything else he will be exposed to, but it sounds like you've got them listening already, which is good.
My older DD went to the same preschool and I know that they will make any and every accomodation that they can for him. She loved preschool so much that real school was a big let down for her, in comparison. In the grand scheme of things I can see how puzzles are just one little thing, but it was nice to have that first 'little thing' responded to in a positive way.
It just struck me as odd when the director said that many of the three year olds entering their program have never tried puzzles before(hence why they have the easy ones, I guess).
