oh that sucks - and unfortunately it won't shrink. my previous popup had a leak around the fan and the back roof side panel swelled like that. As long as the posts stayed tightly attached, i did not do anything about it other than stopping the leak to prevent further damage.
I am not sure if there is a fix other than replacement of the panel. Somebody may have a better idea.
be sure to check all the seals frequently and recaulk anything that looks even remotely suspect (including the main body).
HTT: "EscapeII" 2016 Shamrock 23WS (current)
PUP: "Escape" 2010 Rockwood HW 277 (gone)
TV: "Bruce" 2011 Dodge Durango V8 Hemi Crew
Just us gals (me, Sis and our daughters)
We spend alot of money to go sit in the woods