Drooling can be a sign of nausea. Perhaps she wasn't feeling good because of the heat. Make sure she's got lots of fresh water if you don't have air conditioning. Cats can get dehydrated quickly.
If you're worried, definitely give the vet a call.
Thanks, I called vet & always have lots of fresh water. i'm ordering some cooling pads for them to sit on & keep cool all summer. Vet said to watch kitty. She seems fine now.
I would watch her and try not to worry unless she does it some more. It's possible that she could be having some dental problems, but one of ours had horrible teeth and never drooled. Another drooled every time he was petted. Good luck. I'm glad you called the vet.