Interesting, I see that Florida has lots of wild and naturalized grapes: http://www.eattheweeds.com/vitis-wild-grapes-2/
It looks like a grape to me but I like to take a very close look and compare the leaf shape and colors closely before making an assessment.. Here is a wild muscadine grape for comparison.
Are there any signs of baby grapes? Our vines up here in MD already have multiple grape clusters forming, so i would think you might see some in Florida.