Did you get the job? For a lot of jobs like that they will deny you for being overqualified. I know a guy who had a double doctorate, couldn't find a job anywhere for nearly two years due to being overqualified.
My limited/indirect experience on both sides of the "overqualified" thing is that it's usually a result of the employer feeling threatened this person will supplant them, or the prospective employee coming off as entitled or non-serious. Having a doctorate doesn't impinge on your ability to mow lawns, but if you're making sure everyone knows you're meant for better things, that's a problem.