Tree frog on window

We hear these by the thousands, starting up their peeping like little birds, at sunset. Whole choruses of peepers, especially in the spring, but continuing sporadically throughout the summer. I found this one on our stainless steel grill and moved it to a house window. I wonder if it had taken on the color of the grill.

Notice the yellow colors on the underside. Do tree frogs change colors like chameleons? I don't know.

Postscript: - now that I've done a little research, I see this is the Eastern Gray Tree Frog or Common Gray Tree Frog (Hyla versicolor), and they can change color.