It's VERY VERY rare to have trouble with an ecig battery. They ARE pretty powerful
batteries, but most that "fail" have been mistreated in some way. Besides that though - your description isn't enough to identify the brand - that sounds like a LOT of them.
If you could post a photo, that would help people let you know if you've got a "very reliable brand name" or an "unknown, knockoff" - or the one (there is one) that was recalled...
So - I certainly wouldn't freak out - they're really quite safe, but it can't hurt to learn as much as you can or want about the
batteries!