A little bit of both.
IF you have long fingers and are trying to "Press" the release you risk the finger going towards the trigger from the pressure being put on it. There is an older generation of SERPA with a fence at the top of the release lever that made it much more likely someone would try to "Press" the release.
Additionally, if one attempts to draw the pistol before the release is activated, the SERPA mechanism will jam. Some will try to "Press" harder on the release when the best course of action is to jam the pistol back in the holster which releases pressure on the mechanism.
The best way to operate the SERPA release (at least in my opinion and we all know what that's worth) is to keep the finger straight and give the lower arm the slightest of rotations outboard which naturally presses the forefinger against the release.
Even though you didn't ask, for the same approximate price the Safariland 6377 or 6378 is a much more advanced holster that can't be jammed like the SERPA. (Most dealers stock so many Blackhawk stuff because they get a huge bargain with it, not because it's the best out there. )