I felt the same way when I had to replace a phone battery...which then made me wonder what the point of having a replaceable battery is when you worry that a replacement battery might explode. So my next phone, HTC One, did not have a replaceable battery and I did not miss it. Replacements are too hard to find and besides it's easier to just plug in an external battery anyway.
I see why Samsung went with the non-removable battery on the new phones.