Hmmm,
Tax man always knows how to get every last drop of blood...
I bought a car in Houston as well, I knew I was going to have to deal with the MVD in Arizona. Same story, they hit me with sales tax based on the ORIGINAL cost of the car. So I paid. Then a few months later I got hit with an additional USE TAX from the state. Well F%*#!. that was a suprise. MVD never mentioned it. You may want to make sure CA dosen't have one.
Anyway you have to pay to play....
Regards