I'm not fan of Al Gonzalez (he was on the board of a state affiliate of La Raza, which I detest), but I just don't think there EXISTED laws that would've made someone "illegal" in Texas when his grandparents would've come over (I'm assuming they came around 1880 to 1910 or so, based on his age).
I say this because my ancestors settled on this side of the border in the early-to-mid 1700s or so, and their letters and journals indicate there was pretty open settlement and "back-and-forthing" between this side of the border and that side of the border, both from a livestock and people standpoint (their old logs and journals discuss people they did business with, livestock they traded, etc.). There were even some ranches that actually straddled the border.
I think modern "immigration laws and quotas" with Mexico began in the early 1920s or so, after the Mexican Revolution. During that time, one of my great grandfather's brothers had gone to Mexico to work for an oil company, and there are letters where he's wanting to come back to the U.S., fearing that he won't be allowed to if he waits too long.
Gonzales explained that both his grandparents and his father are dead -- so they can't be asked -- and his mother doesn't know. And that's why he told CNN he wasn't sure about his grandparents' immigration status.
"I was trying to be honest," he said.
He said the only clue he has is that his mother remembers having to go to the post office regularly in the United States. That, Gonzales contends, could mean that family members were taking care of residency paperwork.
But he doesn't know for sure.