Re: Yes it's unusual.
There is a degree of Texas pride that exceeds what you find almost anywhere else in the country for the last couple of generations or so. It's part of Texas culture to talk as if Texas was one vote short of setting up an independent nation tomorrow, but that's "just whistling Dixie". In truth, Texans have a history of being at least as patriotic towards the Union as others--arguably more so. See Rumor of a War for an example. I spent twenty-two years there, and I NEVER saw a Texas flag without a US flag accompanying it. (If you're careful, you'll note I slipped a Texican phrasing in there...) (Note: Mudflaps & the like are not flags...)