Apparently juvenile Cubans sometimes have blue leg bones visible from below and reddish eyes, Cuban Treefrog, and the skin on the back of the head is fused to the skull, Florida Wildlife Extension at UF/IFAS. That might be some help. Your guy looks to have the large toepads and reddish eyes (though accurately judging colour from photos is not always possible unless every step from camera to screen is carefully calibrated, and the frogs can vary so much on their own).

I'm definitely no expert when it comes to Florida frogs or possible immigrants though. Juveniles can be tricky in any case.