<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by Spider:
Also, I have a forced stopover on my return leg. Could this somehow affect the total mileage?</font>
A stopover causes the mileage to be counted point-to-point at the stopover, and no provision to forgive this cost for a forced stopover. Up to 24-hours is allowed before it is classified as a stopover. It sounds like you are being hit by this rule.