Yes, the real odometer is correct and was not affected. Trip A was also not affected. Interestingly Trip B, as displayed on the dash, also did not reset. It currently reads 883.7. The odometer reads 11884. So Trip B has not been reset since the car was new.

From when the car was new until now, I have used about 347 gal of gas (calculated based on avg. mpg). The trip odometer currently reads 883.7 miles. Using those 2 figures gives 2.5 mpg. But avg mpg on Trip B is reading 1.5 today. (I think it might have been 1.3 before and not 1.8 as I reported in my orig. message, and the average is still therefore going up). I thought it might have exceeded its calculation capacity at exactly 11000 miles, then started over, but that's not the case. It had to be somewhere over 11000 miles. Based on 1.5 mpg and 347 gals of gas used, it was about 520 miles ago that it reset for its internal calculations, or at about 11360 miles. (That is just approximate due to rounding errors in the 1.5 mpg figure, and the approximate nature of the 347 gals used. It might be plus or minus 50 miles from 11360 when it reset).

I filled up the tank most recently at 11178 and 11625, and therefore reset Trip A at those odometer readings. So the "mystery reset" was in between those fill-ups, and I'm pretty certain it wasn't anything I did.

I think if I went to the Honda dealer with all this, they say "HUH?" and not have a clue. They can't "duplicate the problem" so couldn't fix it unless other people have reported it and a fix exists. It could also be a one-time electronic bug that will never happen again. It's also more of a curiosity that a real issue. I have owned my HAH for long enough that the lifetime mpg figure wasn't changing much anyway, so having to start it over isn't a big deal.