A couple months ago I had to replace the glass in my 3 year old iPhone after dropping it. Two weeks ago, I noticed the front glass was now bowing out. I figured it was that the glass wasn't properly clipped in. So taking it back to the shop they replaced the glass, they said and showed the battery swollen and black and waiting to explode. it was quickly replaced. I carry the phone in my front pocket. I am glad it didn't explode.