inflated mouse

[Bartman]

i was feeding my tegu a mouse, a pinky, and i fed it to him but he didnt eat it right away he left it in his bowl all night and when i woke up the next morning it looked like someone blew it up like a balloon. it was all inflated and its skin was stretched to its max. very gross looking by the way but my quesiton is he ate it and i wanted to know if this could have been harmfull and why this happenened?

thanks in advance