I do a similar thing - the dry mount press, set at just warm. The prints are separated by double layers of glassine (recommended by a conservator). Then I turn the press off and come back next day.
The prints are nice and flat, but if I store them in acid free boxes (not under weight), in a season change, the edges will start to lift up again. I always have to flatten again before framing (I hang mount the prints behind mattes, not dry mounted.) Even then, later, in the frames, I can see the edges starting to lift, depending on how much pressure there is from the matte and glass, etc.
Is this normal for others?