Ok so update. I pulled out the spa flapper and inspected it. Didn't see much at all, and all the parts looked newish or in good shape.
So I wiped over it a few times and checked the pipe. Not much there either. Hoping that maybe the stabilizer got caught in it, and caused the failure.
Screwed it back together, and the spa did not drain last night. Hooray! Thanks for all your help!
So another somewhat related question.,,how often should the pool be "filled" with water this time of year in Florida? Ever since my pool water line fell below skimmer I've been paranoid I have an internal leak. We did have a massive leak on the pump which has been fixed, but I always feel like the pool water seems lower then it should be.
Considering I'm in a screen enclosure and it rains everyday, I figured the hot 100 degree weather would only have a minor affect on the pool level.
Thoughts on this?