San Houston asked that when the Civil War was happening, that Texas become a Republic again and not join the Southern states. The reason? Texas has a history of being a place that was a liitle beyond and above the rest of the Union.
I'm not sure I agree with this statement. From the Handbook of Texas Online article on Houston:

Houston always characterized himself as a Southern man for the Union and opposed any threats of disunity, whether from Northern or Southern agitators.

Adamantly opposed to secession,qv Houston warned Texans that civil war would result in a Northern victory and destruction of the South, a prophecy that was borne out by future events. The Secession Convention,qv however, convened a week later and began a series of actions that withdrew Texas from the Union; Houston acquiesced to these events rather than bring civil strife and bloodshed to his beloved state. But when he refused to take the oath of loyalty to the newly formed Confederate States of America, the Texas convention removed him from office on March 16 and replaced him with Lieutenant Governor Edward Clarkqv two days later. Reportedly, during these traumatic days President Lincoln twice offered Houston the use of federal troops to keep him in office and Texas in the Union, offers that Houston declined, again to avoid making Texas a scene of violence. Instead, the Raven-now sixty-eight years of age, weary, with a family of small children, and recognizing the inevitable-again chose exile.

-- http://www.tshaonline.org/handbook/o.../HH/fho73.html
Of course, this is just one source, but I can't imagine Houston working so hard to get Texas into the Union only to take so easily out of it. If you have a source for this information, I'd love to see it and add it to my lecture on Houston for my classes.

T.