I would run it by a discrimination attorney in TX. It doesn't sound like they are operating in an above board manner.
My answering this question does not form an attorney-client relationship. Always retain a qualified attorney before taking any action.
Please remember Texas is an "at-will" employment state. Employers may discharge you for any reason or no reason as long as it is not based upon a protected trait. Those traits being: race, color, national origin, sex, age, or religion.
If you feel your employer has committed an unlawful employment practice, contact a local employment lawyer as soon as possible.
In fact, there is no legal obligation for an employer to provide a statement of grounds for termination unless there is an employment contract or union agreement that so provides (a very rare circumstance). Many employment attorneys who practice employer-side law, consistently advise businesses and employers to make NO statement of grounds when terminating an employee. There is no upside to the employer in ever making a statement of grounds.
If the employee files for unemployment benefits, at that time there is ordinarily required a statement of the employer's reason for termination. In some circumstances, even then the employer's interests are better served by waiving objection to the claim and keeping silent as to the reasons for termination. Hence, the only way to truly "force" a statement of the reasons for termination is to commence litigation.
My responses to questions on Avvo are never intended as legal advice and must not be relied upon as legal advice. I give legal advice only in the course of an attorney-client relationship. Exchange of information through Avvo's Questions forum does not establish an attorney-client relationship with me. That relationship is established only by individual consultation and execution of a written agreement for legal services.