If the O2 sensor code did not come back on after erasing it from memory,
it's a soft code. Don't worry about it. Something might have triggered
it, then stored it.... which is what it's programmed to do.
Just to be sure though, is the harness for the O2 sensor near your spark
plug wires? If so, re-route it away from them (especially if their High
Performance aftermarket wires)...
Just take off the sensor, disconnect from the harness.... check the wire
for any cuts or fray's. Reconnect sensor, and make sure to apply some
anti-seize on the bung. Wrap it up with some protective wire loom....
Just things to consider, but again, if the code did not come back, don't
worry about it.