The same thing happened to me at a Toyota dealership. Weird. It must be in the Universal Salesman's Handbook.
And like your husband, I told the salesman that I'm not signing a napkin. I'm not signing anything at all.
It remains one of the more astonishing experiences I’ve had.
I have to say the guy at the Mazda dealership on that same trip (we were shopping for our daughter) was great. We didn’t buy a car from him, but I’d definitely check them out in the future.