This is just a guess so take it for what it's worth.
Glasses make an indentation in the skin. The sensation you feel when you are wearing them is from the pressure the weight of the glasses apply. My guess is the flesh under the area remains compressed after you remove them and you can feel it until it returns to it's normal shape.
To test this theory, put a piece of gauze under the pads of the glasses for a while. That will distribute the weight over a larger area. If the sensation is no longer there when you remove them, that would explain it.
Answered Aug 10, 2010
Edited Aug 10, 2010