I found the solution... While working on a friends bike he brought me with what? conveniently the same problem. Cables are sticky. Wouldn't expect it on a new bike but apparently some genius at the bike shop failed to oil the cables before installing them so when the shifter pulls it gets the tug of the derailleur as well as the resistance of the cable housings. This causes the shift to fail do to the huge tension and the bike to jump back up a gear. So if you're having this problem remove ur cables and lube them then reinstall and readjust.

- Rufio