sometimes even if we have time to react in a non aggressive manner things go array,possible employer sanctions,but i don't think so. you had the proper intentions,marks probably not visible in a day or two.next time maybe a strong verbal warning.
probably spark knock causing valves to rattle or ping as it is called,2 causes come 2 mind,fuel octane 2 low, or faulty fuel ,water content,or engine timing needs 2 b reset,change brands of fuel 1st ,listen again,react accordingly