I got the same analysis as you, that the bike was running lean. It was also idling really low as well and "coughing" at low rpms as opposed to actually backfiring. It still "coughs" during warm-up, but once she's warm the engine is smooth all the way through the power-band. So what your mechanic told you must be pretty accurate as my mechanic reset the fuel map to the defaults and tweaked it from there to correct the issues.
As for my question about how often this has to be done, it was for informational purposes and not to report that this adjustment has had to be done for my bike repeatedly. This is the first adjustment, and with hope, the last adjustment of the fuel map on my bike. I got in about 200 miles yesterday and the bike ran superbly so perhaps this is, as you said, and isolated incident.
Thanks for your input, Gashouse! Ride safe!