Does the OP want a smooth trip or does the OP want to take risks in the hope of saving 90,000 miles by some mistake not being discovered? Personally, I would opt for the smooth trip because I would feel too guilty about suspecting an error and not pointing it out to DL. I would call DL and ask the agent to look very carefully at the reservation and ticket to verify that everything has been done correctly and both tickets have been reissued in FC.