The striker, who recently joined the Cottagers from Leeds United for £11m, played the full match at Fir Park on Saturday afternoon.
"I thoroughly enjoyed it, coming back to one of my old clubs, and it was good to be on the winning side," McCormack told Sky Sports News.
"I only joined up on Wednesday so I have only done three days training so I didn't think I would be playing today and then I played 90 minutes so it was a nice surprise.
"I can only just add to the group that is already here. There are some very good players here. We are still only two weeks into pre-season, there are four weeks to go so there is still plenty of work to be done."
Fulham get their Championship campaign underway against Ipswich Town at Portman Road on August 9.