Well I went ahead and loosened the retention screws until the point where they were just wobbling in the holes, and then tightened them back to where they just stopped wobbling. The gun will actually leave the holster fairly smoothly now (unless you get a bit of a radical backward pitch on the draw), although there is really not any kind of "locking" action as it goes into holster anymore. The gun is basically just held by gravity.
If I slowly turn the holster upside down with the gun in it, the gun will drop out just as it gets to perfectly vertical. That is with no mag in the gun, btw. Is that normal, or should they normally have more retention force than that?
If that is how it's supposed to be I'll just have to loc-tite those screws in so that they don't come out somewhere along the way.