(excuses for my bad English in advance)
I had a similar problem in my HTC desire X. Sometimes lockscreen didn't show up, in other moments it worked, but doing strange things. I was able to use my launcher gestures (i'm using exposed gesture navigation) and even launch apps(that sounds great!) but the phone wasn't totally unlocked and the pi lockscreen was somehow in background, causing rare things, like not showing lockscreen. I disabled the gestures for the locker and now is working perfectly. Hope it can help.
But now I miss the option to launch apps from lockscreen. The configuration of the gestures would make this app mind-blowing!
Sent from my GT-S5360 (Galaxy Y)