Did you make sure to mount it over the wife's car and not your vehicles?It has a built in brake setup that seems pretty stout. It's a solid metal piece that clips in so it can't unscrew. I do like the idea of having extra safety built in though.
I will say, I'm less worried about it unraveling and more worried about how well I hit the studs in the ceiling. I've never hung something that heavy to a ceiling before. Yes, there are 10 lag bolts per side, but still....it's a very scary situation when you have nearly $80k in vehicles sitting right beneath it. After a few days I'll feel ok parking the cars in there again.

But I would add some chains that mount into the studs and attach around the RTT base just for the extra piece of mind. One is none, two is one kinda deal...