Pete Sessions was against Parker Griffith before he was for him

Thanks to our Sessions Watch readers in Alabama who sent this latest bit of flip-floppery; when Parker Griffith (AL-5) was running as a Democrat for Congress, the NRCC ran this ad against him:
The NRCC effort failed, and Parker Griffith won; but today, the conservative Democrat switched parties, and is now a Republican. So now, Pete Sessions is lavishing praise on Parker Griffith:

Sessions: Congressman Griffith’s party affiliation may have changed, but his conservative principles, values and commitment to Alabama families has never wavered

So...if he had conservative principles all along, what's with the ad claiming he has "shameful conduct and can't be trusted"?