Yes, I think so. You are required by Law 81C6 to deal with all matters that come to your notice.
Incidentally, I agree with you over the unnecessary pre-alert. There is a type of bullying good player (fortunately very rare in England
but sadly a bit more common in North America
smile: that tries to use the Laws and regulations to his advantage. Best is always to produce the Law or regulation in print and read it out.
The general approach to a revoke not noticed by the players is to wait until the next hand or round has started so there will be no penalty tricks for the revoke but to restore equity under Law 64C, ie return tricks lost by the revoke but no more. If you think ten tricks would have been made without the revoke your ruling is right.