mushroom?

Can somebody enlighten me as to what it meens when a tip "mushrooms".

[Rod]

The tip compresses and it mushrooms out or gets larger than the ferrule it is glued to. It should be flush with the ferrule. The overhang leaves a softer sidewall since there is no support. That can cause miscues with too much side english. Not to mention it is annoying looking like a swolen thumb sticking out there.

Thanks, that's what I thought but I wanted to be sure.