I have about three eGo batteries. They don't seem to hold a charge long any more and one of them when I take a long drag, it will blink twice and stop. I know it's supposed to do that, but I don't think I have ever seen it just blink twice while letting go, so I can drag again. What I mean is normally I can take a drag, it blinks, I press the button again and can do cycles like that. Now when I do it, it blinks, I release it and try again. Almost a second later it blinks again, instead of about 5 seconds. Is this a sign to replace the battery? I think I have had it about a year, using it constantly.