Hopefully the result of the incident wasn't too serious -but- the post incident diagnostic all led to the same culprit - you had a poorly made servo extension cable between the receiver and the servo(s) and vibration loosened 1 until the servo was no longer receiving signal from the receiver.
Now there are plenty of ways to deal with this - you could:
Well before you quit, why not check out the slickest solution of them all - a safety clip built in to the servo extension itself! It's a flexible plastic, it won't snap if you bend it to remove the servo, you can bend it right back -and- it adds almost no weight to the overall setup. I've attempted to photograph the item at every possible angle, however if you need to see something not in the pictures, send me a message.
Try a few and see - then when you realize you can't live without them, buy more 5 packs. I'll eventually be listing them in all the common sizes (15CM, 30CM, 45CM, 60CM & 90CM), in both JR/Hitec & Futaba color schemes so if you need a length you don't see here, send me a message - I'll be able to help. Want to buy in quantity for your whole club - I can handle those orders too.