Mike Leach could be petty and petulant. While I am sure that Johnson regrets how things played out, no one would understand his reaction better than Leach.
Greg McElroy (former Alabama QB who originally committed to Leach at Texas Tech and then de-committed to enroll at 'Bama) shared a story on ESPN about the first time he encountered Leach after his playing days were over. He was assigned as the color guy on one of Leach's games. He approached Leach with "Coach, great to see you, Greg McElroy" whereupon Leach told him that it was a pleasure to meet him. McElroy was surprised and hurt that Leach didn't remember him. He later learned that Leach regularly pretended not to know players who had de-committed from his programs. The next time he encountered Leach, Mike greeted him like a long lost friend. He thought Leach took pride in the fact that he had identified McElroy as a legitimate college QB before anyone else, even if his success was ultimately with another program.