Thanks. I'm willing to lay down money that it is not a gray; the pattern and skin texture are just wrong. Florida greens are not all that close to northern greens in body shape; ours tend to be much more robust, like this Tennessee green:

Hyla squirella is definitely a possibility; in that case it would certainly be an introduction and not a natural range expansion. The defined border of the white lateral stripe makes me think it is not squirella, but I'm not familiar enough with that species to know how much that varies.

Hopefully sometime this summer I will be able to head up your way and see this population in person; I'll send you an email before I do.