screen rubber mark, not bonded on yours.
not too bad a job to take out, start down one side and peel the rubber over the lip from the inside, takes a bit to get it started but once it is going its just a case of being patient and working your way around the sides and along the top. the corners can be tricky and don't worry about going along the bottom too far each side as the screen will lift out once the sides and top are free
Whatever anyone says DO NOT try the fairy liquid and press with both feet routine.
YOU WILL nOT get it out in one piece or crack free.
Do what Kev says. It is the only way I have ever found of getting it out in one piece.