Had mb service two weeks ago included panam roof, when I looked there's what looks like white lube, smeared around parts of rubber seal under glass. Don't know what they use but definitely white now.
I suppose that's the idea, there's a lot of mechanics involved in opening and closing, so if it's dry and unlubricated It would. Gummi pflege is often recommended on here, as opposed to a grease, apparently it doesn't attract dust and grit which would be detrimental.