I think I am having an identical issue on a light of nearly identical age. I will try to turn the light on after about a week of little use, and the battery will be dead. Is that your experience?
For those of you with a 120 lumen L4 also, is the LX2 a reason to give up the L4? I just acquired a new L4 in trade, and I figured before I decide to keep it, I might just go for the LX2 instead.