Absolutely.
My customers expect me to look after their best interests, adding a half hour and two $2 O-rings to the bill is hardly "ripping someone off." Not doing so on the other hand, is common garden variety incompetence.
At 30K, wouldn't it still be under warranty Glenn, and doesn't this imply that they [the customer] have absolutely no trust in the dealerships methods?
I'd much rather explain the difference in price than explain why the vehicle has the same failure after a short period of time, and since I have yet to see one where the O-rings in question aren't shriveled and cracked, a little show and tell with the customer makes it all clear to them (unlike you).