2008 XC70 Door lock question

[AAKNJ]

I recently had a problem with the drivers door lock in that it would not allow me to open the door from the inside to get out of the car. The outside handle opened the door with no problem. In trying to get the door lock to release, I just happened to press the black rubberized button in the door handle (on the outside) and it seems to be working now. Cannot find anything in the owners manual that describes this condition or that button. Anyone have any insight? Thanks...