Had I not noticed this, I might have accidentally forfeited the entire hotel reservation as a no-show, and that would have been bad. Besides the fact that Lisa is recording the "Fannish Inquisition" and I'm running the Probability & Statistics Seminar, this year's SMOFCon is an SFSFC event, and I feel rather obliged to be there as Secretary of the corporation's board of directors.
As an incidental side effect, I also realized that I had taken the original time off out of the wrong "bucket." There's a bucket of accrued time off left over from the days before XPO bought Con-Way/XPO that I thought I'd have to use by the end of 2018 or lose, but it turns out that it's usable through 2019, and consequently I'm better off using currently-earned PTO now and using the so-called "no-loss carryover" next year for part of either the Westercon/NASFiC or Worldcon trips, or even next year's SMOFCon (which I hope will be in Albuquerque, although that won't be decided until this year's SMOFCon.)
Because of the holidays, SMOFCon, and at least one other day I expect to have to take off in December to do something I want to do, it looks like six of the next seven weeks will be only be four (or three) days long for me.