I've had shit break. The fun part is figuring out what broke out of the 5000 things it could be.
Discussion
The fun part is when the problem only shows up once every few days and you have no idea why.
A while ago I was having problems with CPU and memory use spiking which could only be alleviated by restarting the webserver and the instance. When I updated rebased it went away for good. I never learned what the problem actually was.