Yeah, it happens on my PC too. Mouse control on the PC is a bit borked. I have the issue you describe and also, when I try to choose from the list of choices at a merchant (i.e., weapon, armor, potion etc), sometimes the mouse click doesn't register. Especially with the MISC choice - clicking on that pops me out of the menu. On ocassion, I select the wrong dialogue choice, even though I had my desired choice highlighted when I clicked the mouse.
In addition sometimes some of my keyboard key pushes don't register during battles. I sometimes have to push the Z key (shout) several times before it finally registers.
I've had all of these since Day 1 and none has been fixed in any of the patches.
All "lovable" quirks of a great game, but annoying none-the-less.
I'm not smart enough to know why this happens, and I don't play on consoles, so I can't speak to that.