The money was certainly deducted from your paycheck in the form of reduced bargaining capitol during negotiations.

"Spirit sued its pilots union in federal court for the Southern District of Florida, accusing pilots of “an unlawful job action,” designed to hurt the airline’s operations. Spirit pilots, represented by the Air Line Pilots Association, and the airline are at odds over a new collective bargaining agreement.

In some cases, the airline said in its complaint, pilots are even turning down a chance to make 200 percent of their pay for last-minute assignments. Usually, the airline said, it has no trouble finding pilots for those flights. Spirit also said union members have “engaged in a campaign to threaten and intimidate other pilots” who accept those and other last-minute assignments." -Skift