To clarify, you should make sure that all of your seals are firmly in contact with the outside of the trailer. "Flush" means at the same level, and you slide is actually sticking out from the side when it is closed. The slides on my 3905 have a slight gap in them when closed (1/4 inch at the top, and 1/2 inch at the bottom) but all the seals are compressed against the side. If you adjust them tight against the side, I think it would put too much pressure on the exterior slide trim. This is just my opinion though, and I am by no means an expert. My dealer adjusted the slides after my PDI, and explained it to me, and I agree. By the way, when I did the PDI , 1/2 of the seals on the big slide didn't even touch the trailer.
2013 Voltage 3905