We also have a 2009 2501SS. When our slide goes out it seems the top seals first and then half a second later the bottom seals. As for pushing the walls, I haven't noticed this. When I am watching the slide going out from outside, it almost looks like it is going out at a tiny bit of an angle and then once the bottom seals, it evens out. We have had no pressure or leaking issues at all.
- 2009 Rockwood 2501SS Ultralite
- 2007 Chev 2500HD
Southern Alberta, CANADA