Don't worry about it. It happened twice, but that also means that its also working corectly since it fixed itself after the first error.
I have a feeling that its gonna do it again, but I don't think anyone is going to notice. The only time when anyone is going to notice is if you did a smog check at 122,500 iles and then did it again at 122,000 (when its suppost to be at 123K). I think its highly unlikely that you will be required to do an emmissions check so soon. But that would be te only way for the DV to know.
Actually one other way would be to bring it back into the dealer for service. Say you brought it in last week for a brake job and then again this week for an oil change. Then they will be like WTF???
But seriously, don't worry about it.