You may have a poor connection where the relay plugs into the socket. I highly doubt the relay went bad in one year. I assume it was new.

I had the same intermitant problem that haunted me. It would occasionally not start and die when going over bumps. Never long enough to trouble shoot though. Eventually it stayed bad long enough to trace a 10 ohm resistence at the connection of FPR coil socket. I had to put additional pressure on the "spade" connection inside the socket so it gripped the relay better. Problem solved after replacing about everything else.

When you inserted the new relay more force may have been applied making a better connection. For the moment, at least.
--
Paul NW Indiana '89 740 Turbo 140,000