No, what the OP was referring to was something different, so happens I've been tracking IAD/DCA-YYZ fares recently and last week there was a jump with the previous lowest fares on UA and AC being pulled... not an issue of qualifying for lowest fares based on a given itinerary but of the less expensive fares no longer being out there. Temporary I'm sure, as I've already noted UA has returned fares closer to normal already (which can be booked on the AC non-stops via codeshare in fact).