What browney is saying is not nearly impossible I'm afraid ! i have done this several times on my hyper 8 port.This has happened to me when the battery runs low on the starter box and i was using a hot plug, i have been able to do this on my airplane two strokes aswell if started by flicking the prop with a chicken stick.If you keep that battery well charged up and make sure you make good contact with the starter wheel all should be well, its no big deal and don't worry about it.My hyper runs well and i have`nt had it happen in a while, maybe one of you technical type guys can give a better explanation of this.What im getting at browney is not enough power/momentum from the start box or bad contact with the wheel plus a hot plug and the piston coming to TDC possibly pre igniting the fuel (not sure about the pre ignition).