Z Axis gone crazy

Has anyone had their z axis climb up after a print with no intention of stopping? It only happened once and thank god I was around so I was able to hit the power. If I had not been there I’m pretty sure my printer would have been in bad shape. Just wonder if anyone has heard of this. I’m super scared to print now without being around as the the job completes.

Nope, only time I have seen something like that was with a computer attached print where the computer locked up, a Rambo board with a failed fan that overheated in motion, or with a 3d printer trying to print a mostly invisible error spline sticking up from a part. That motion would be viable in the gcode preview though.