if you create a selection that extends several lines — e.g. by entering select mode with v and then extending the selection down a couple times with j, j, j — and then scroll horizontally you'll see the selections extend past the end of the line.
I thought this was handled already, but maybe it's not? It's kind of looking like it might be some offset issue but I'm not sure why exactly this is happening. Not a big deal for now though, can be fixed later.