It's the shifter. Front upshifts on under-bar shifters have always been like that, and some people hate it. I'm a 5'11" dude with big hands and a pretty strong grip, and I despise all under-bar shifters for exactly this reason. A front grip shifter or thumbshifter won't do this, but neither are indexed, and the asymmetry bugs the hell out of a lot of people.

Thumbshifters are the only flat-bar shifters I like. I used to like GripShift a lot, (8-speed X-Rays,) until I blew apart an XT rear derailleur trying to make a standing bail-oui downshift at full honk. And cable replacement on them has sucked since 1988.

--Shannon