Is it a delayed flicker? That's the flicker that you see in the complete mode. You'd wake up the screen, sometimes a second could go by, then a visible flash of the lockscreen sliders (that flash is the OS letting us officially through the lockscreen). Lite mode never asks for that official stop. The only time the stop happens is if you press home, and when you that you'll see a flash that is similar but a black screen instead of the lock sliders.
If it stayed on during a call, you get a lockscreen when the phone is designed to never have the lockscreen. In other words there is no lockscreen to exit while calls are in progress, so all versions of myLock disable during phone calls to avoid causing lockscreens that shouldn't happen. This also means that if you press home to do things while in call, but allow the screen to sleep, you will have to slide to unlock. The OS only disables the lockscreen while the phone screen is up. I think that it will be possible to prevent that in future beta releases, but I am not sure yet. That one's on the pending list along with whether we can have myLock let you answer a call with the power button instead of the unlock slider.