Chocolate Train - did 1 waste a day on my multicountry Flexipass

I think I screwed up :-(, I purchased a reservation for the Chocolate Train out of Montreux for $56 per person (rate for Eurailpass holders with multicountry pass including Switzerland on RailEurope's site). Even at $56, with this appearing to be a reservation only, is this going to use a Flex day on my pass? If so, I need to make sure I save one of my Flexi days for this.