I had the exact same problem on a scope i had mounted (by a gunsmith) on my 30.06.I don' t agree that the screws were not tighened down to avoid scope damage (ie gunsmith).I also use Leopold rings but do not take a chance on scope movment.I now install all of my rings and scopes as well as some friends' my personel remedy is to Lok-Tite ALL of the screws and also a dab at the top of the ring, front and rear . It maybe over-kill but no-one has complained yet!

Just my 2 pesos