While I dont condone taking frogs from the wild I know that Grays are very abundant in our area (I like in Illinois). In fact there pretty abundant in most area's of the US. But wild Grays seem to be very healthy creatures. I've heard many people take in wild grays and have no problems with parasites or the like. I even had mine sharing a tank with a captive bred green and Percy (the green) never had any problems (well, not after Helly got over "throwing her weight around" X3 ).

Since you have a wonderfully set up tank and you here in case something does go wrong then I would say you could enjoy your little Abby for a very very long time!