From my limited experience, cobs don't last forever. They are super inexpensive, which makes them a great choice to smoke while mowing the yard, camping, or using real strong aros. Unfortunately, the cob material will eventually wear thin and in some cases burn through.
To fix this, or even prevent it, make some pipe mud out of hardwood ash and saliva. Apply it to the bottom of the bowl, and allow it to dry for a day or two. This has greatly extended the life of my cobs.
I believe that the most common factor in a pipe getting that hot is when the smoker if puffing too hard and/or too fast. Slow down, and sip the smoke.
Good luck, and welcome to the forum.