Twists Won't Turn Off

[Noddy1]

I have four Ego-C Twists, two 650s and two 1100s. I have a hard time getting the 1100s to turn off for some reason. I do the quick 5 press thing and the light flashes like it turned off, but if you press the button again about 5-10 seconds later it lights up. Sometimes they turn off as expected, but that's doesn't happen very often. Has anyone else had that problem?