the 30.5 miles was counting down backwards. That is the distance you have left until the gauge is married to the ecm and can no longer be used in another bike.
Oh right, cheers for that!
Hmm, But that would seem to mean a new, new speedo, on a new bike. Oh well, as they say, 'Everyday is a school day'.
T
FWIW, I bought both of my bikes used, so I reset trip B at the time of purchase. Trip B will always show "my" mileage on the bike and like Spartanden, I use trip A as a range marker.
You could have just wrote it down when you bought it. You can still subtract it from the total.
Going backwards in time, being down to one tripometer. Another thing it took Harley years to copy from the japs.