Apple tree leaf curling

Hello all!
We planted a new apple tree sapling about 3 weeks ago and it has been growing very well. This past week I noticed the leaves curling in and upwards.
Anyone know what the cause is? There are no parasites or fungus that can be seen, and although we had a good 2 week drought, I did water it daily. I live in northern Illinois.

Do the leaves look green and healthy otherwise? Can you post a picture?

Daily watering is probably overkill for an apple tree. It should get about an inch a week (a five gallon bucketful, roughly), and it would be preferable to deliver that in one watering if it's practical. Not sure that's causing the leaf thing, but I just mention it incidentally.