RMR question

Anybody that uses an RMR on your CCW: have you ever had your RMR brightness turn down low by accident? I was carrying at 4, and my gun was hitting the back of a wooden starbucks chair for a few hours. I got home and when I checked to see if the glass needed cleaning I found the RMR was turned all the way down. At first I thought it was the battery but I turned up the brightness and back to normal. The (-) button is outward facing on right handed draw. I think I was brushing that button up against the edge of the chair. I’ve got cowitness sights so it wasn’t a critical failure but would have definitely caused unneeded complications if I needed to draw. Anyone else have this happen? Can you lock the brightness setting in an RMR? via /r/CCW https://ift.tt/34oHbMr