Stik
I have had several prop stops with a carb Lycoming doing spinning trials in a light GA aircraft. Never did find a reason. Could not repeat to order. I suspect that quite a few engines can quite easily stall at idle when thrown about at very low airspeeds and with funny prop gyro effects etc. I would not let it bother you as there is no reason it will not start again under normal conditions of flight. It will of course be an F’ing nuisance so far as your sequence goes but that is not a safety issue. If your height does not allow enough IAS for a dive restart there is no harm in using the key of course. In fact if it ever happens again why not go for the key at once and give yourself some confidence? The worst problem I ever had with this stopping business was with the Lycoming 540 in an Optica. Since it was driving a ducted fan the RPM always went to absolute zero if there was ANYTHING wrong with the idle and you had no option except to use the book ground hot restart as the donk got NO help from the fan. In said Optica this called for 7 actions in sequence using both hands. So if you had it out of trim and happened to be at low level it was time to use the knees. Best thing was not to throttle all the way back while you depended on the donk - as in the circuit.