This basically confirms my theory.
I don't see why this poll isn't reasonable. If Obama trails Romney by 7 and Gingrich by just 5, I could definitely see Palin being tied.
Palin's still doing no worse than Perry after all the nonstop olympic sharkjumping she's engaged in... I know Perry's always been pretty damn weak incumbent for someone who's been in office this long and never even had a seriously close election, but... there's definitely still room between her current polling and rock bottom.
I'm not sure of the location of the city boundaries of Denton and Fort Worth, but they would have to be dramatically elsewhere from where you'd logically put them for Obama to have lost Fort Worth or polled just 51% in Denton town.
The rest of the Denton County is exurbia (suburbia to the far southeast) and largely dreadful for Democrats, of course.
Obama only won Ft. Worth city with about 53% IIRC. No surprise he lost the county (by almost exactly the same margin as statewide interestingly--bellweather county?) considering the political makeup of Texas suburbs.