From what I know and from what I've researched, this is not uncommon for V-Twin engines. Especially for air cooled engines where the rear cylinder gets less air flow to it. With a liquid cooled V-Twin, I have seen where there are still other factors that can have the same effect, but are not as prominent due to the liquid cooling. I wonder if that is what is going on with mine. Either way, the AutoTune will fix it