Yep, let her out. She'll be fine.
My sister once trapped a stray and took him (Seymour) to be spayed. The vet said he would be tired and out of it and to keep him confined for the weekend. We set up the master bathroom for him so he wouldn't want for anything. After 5 minutes, we heard a crash and went to check. He had jumped up to the bathroom window (about 4 ft up) and forced it open and escaped to the backyard. He came back a few days later and never left.