I was wondering about that. I haven't pulled it out yet, but the guy said it was a small hole in it. So I'm not sure if it's from rot or impact. It looks like a fairly thick burly gauge of metal. So I don't know if it's more likely to be rot or damage.
We have had several people break in at work and steal the fuel from our box trucks. Thiefs don't bother with siphoning fuel anymore. They just punch a hole in the tank and let it drain into their gas can! Such a pain in the A$$.