I carry a SA XD40 on duty in a Safariland SLS holster. When I am just at the range, I carry in a cheap Don Hume open top of some kind. During fast presentation drills, I find myself trying to find the little lever hook to open the hood so I can draw.
Likewise, when I am in the Safariland, I put my hand down to draw the weapon, in the "watch your target, getting ready to go to cond. red mode", and like magic the hood is down. I don't remember how it got down, I just know it goes there. And when the gun goes back in, the hood "magically" goes back up. Muscle memory is not just a fad. It is the truth.