Obviously, this is all simply thinking out loud, but, there could possibly be an erroneous signal. Perhaps a power spike/drop that could've caused the code -- certain "mechanical" anomolies such as a loose connector activated by a bump in the road, perhaps oxidation, etc -- those "quirky" little "demons" that cause electronics to get our blood pressures up and our paranoias working overtime.
So, you're saying that there has been no noticeable difference in shift? And your trouble code has gone away? I would be thankful
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I, personally, wouldn't worry about it unless the code recurs. Of course, if you're genuinely concerned, I'd head to my favorite Suby shop, dozen donuts in hand, and ask for a hook-up to the select monitor.