Frogs are coldblooded so it's generally good to give them some time to digest. He might be a little hungry, but not too much.
Grays might just be small enough to require daily feeding. On the other hand, American Green Tree Frogs are about Grey size and I've seen several recs for feeding them every other day to every two days. My suggestion: stick with what seems to be working. Edit: There's recommendations for feeding Greys as much as they'll eat for 15 mins 2-3 times a week. But if you're handfeeding and the frog won't eat that much at once it might be better to feed less and more frequently?Here's a caresheet from this site.
Here's a caresheet, it sounds like you're already doing the stuff on it, but here it is anyway.