That is exactly what he was talking about, and I also agree with his prognosis. The screen is not sitting properly in its place, likely because its place is tweaked.
You make a very good point, one that I had not considered. The focusing screen is frameless, therefore a new screen would likely do no good. It would almost have to be the seating in the camera body. Best have a pro look at it, if it's something you care about. Personally, that sort of thing would drive me nuts, and I would be delighted to spend whatever (within reason) getting it fixed.
I am beginning to resent being referred to as 'half-fast'.
Whatever that's supposed to mean.