Unless the Texas Motor Vehicle Title Manual has been changed since my 2004 copy was printed, they deviated from standard procedure. That was a good break for you. My Suburban was titled by body serial number in Colorado and I had no trouble getting it titled that way in Texas. I don't know if the rules have been changed or if the clerk didn't know the rules. But I'm happy with it.
But like stated above, it all depends on the state and sometimes on the office or clerk.