Gambá (Opossum)

I was in a trail trough the Atlantic forest when I almost stumbled in this opossum. At first I thought it was dead, but then I saw it move slightly, trying to reach one of the many flies that covered it. I took a small branch and shook it gently, thinking that that could make it to react a bit, but it just stood there, still. I left it there and took my way in the trail. Around one hour latter I came back, and it wasn't there anymore. Since no one has passed by the track besides me, the opossum must have gone by itself. Now I have a doubt: did it recovered enough to go away, or was I tricked by a master of deception? I think I'll never know...
As an adendum, I learned that opossums REALLY play dead when fill threatened!