So the shim on the dry side is stuck. I'd still use a razor blade to try to gently pry it away.
There is no adhesive, so nothing "sticks" as far as I've ever seen (i've owned 3 MP10s and currently own 2 MP40QDs). But I could see where that rubber spacer might get stuck over time. The key would be to break the seal underneath it gently with as flat of a blade as possible, and keep the blade as parallel to the glass as possible.