I question whether it should have been aired at all. The TV station — WFAA — seems to be taking advantage of its access to the President, but given the attention this local TV reporter — Brad Watson — has received, there's an obvious incentive to exploit after-interview material like this. And it's not like Brad Watson will get access again. Obama's reference to "next time" is, essentially, a joke.
But I want to talk about the quote I extracted. What "historic reasons" is he referring to? It's actually not true that "Texas has always been a pretty Republican state," unless by "Republican," you mean something other than the Republican Party. I suspect that his stumbling — "you know" — covers some thought processes. My guess: He knew he was fudging, and he was deciding how clear or veiled he wanted to be in insulting Texas.
ADDED: Instapundit says:
Apparently, when Obama taught Constitutional Law he never got around to teaching the Texas White Primary cases. Or talking about which side was which in the Civil War...