Lynn- those big adorable eyes don't look like any native treefrog we have in Canada.
Do you live near any greenhouses or other places that might get shipments from overseas that harbour stowaway frogs? More than one frog has been found in produce from a grocery store. Not generally from Africa, but stowaways happen.
Perhaps someone from a nearby city or town set it free in your area. And by 'set it free' I mean 'condemned to a cold wintery death'. I would keep it (in it's own vivarium as mentioned) or find someone who wants it. Since you already mentioned giving it to a pet store I have to ask- you don't happen to be in Southern Ontario do you?![]()