Nope, I literally see it as the valve getting closer to the cylinder wall as the lift increases.

Yes, the starting angle is such that the valve intially starts on-center, but that very angle also has it moving towards the exterior cylinder wall. I mean theoretically if you kept on going it would simply run into the wall.

Having said that, I suspect that given the lift ranges most of us are talking about (street builds), so maybe .650-.700 at most (?), this probably does not hinder the air flow much.

Further on, I suspect that the shrouding due to valve diameter size has a much bigger role, especially the part of the valve head closest to the cylinder wall. This I believe is part of the reason why doing a de-shourding cut on the combustion chamber often helps with the flow.