I am the resident expert on this topic! Sorry Brian...
So my issue started with my larger side by side windows on the dinette and sofa side. One window was lipped, the other was touching but also very loose. After lots and lots of debate Dynamax sent double pane insulated windows, they are very nice, no rubbing, lippage or rattling. Now while at the dealer THEY brought to my attention the other side by side windows had the same problem. The dealer attempted to adjust them but they still touch at the bottom. Running them in and out causes occasional rubbing and lippage. So the debate on what to do rages on...
My thoughts on the cause are either the frame is too weak or not properly supported in the opening thus causing the sagging and shifting or the opening may be out of square and it is pushing on the frame, again causing the issue. The dealer isn't to sure. They felt one of the openings were tight but the other seemed fine.
I have looked at 4 other Dynamax units with the same or similar windows. I found the issue on two of the four units and not all windows were effected. One was a Isata 5 30FW, the other was a DX3. Both units had windows rubbing and touching at the bottom. The other two units were a Isata 5 35 DB and. 2017 Isata 5 36 DS. The windows on those units were all perfect.
Maybe the issue is Lippert? It's possible they had a bad run... just guesses here. There doesn't seem to be any rhyme or reason. But my issues have not been resolved. According to Dynamax it is normal for windows to rub and sag. I had to drop my coach off at Ram yesterday so I took the opportunity to stop at a RV dealer in route to ask about new windows. I showed them mine, they agreed that something is wrong, we looked at units they had, Jayco, some fifth wheels, similar windows. No issues and looked good. He felt mine were a problem. He didn't agree with them sagging or rubbing, he felt that would be a problem.
Below are pictures of some of my issues. I would suggest you look closely at whatever your buying.