throttle cable slid off

[boxster]

I have a non e gas base box and Yesterday when I started the car I realized that something was wrong with the accelerator pedal, it went all the way down but the car didn't move or rev. So I opened the engine compartment and found that the throttle cable had slid off from its place, near the throttle body. I put it back in place and now it seems ok. But I found it very odd that it had slid off by itself, especially since it gave me no signs the day before. I checked to see if its still in good condition and it seems ok near the throttle body, not frailing or anything like that. Has this ever happened to anyone, and any ideas why this could have happened? Luckily I was in the garage when it happened, I wouldn't want that to happen whilst stuck in traffic!