Keep ALL documents, text, voice mail, email, etc... Contact a lawyer. Many will take your case without any downpayment, collecting a percentage only if you win.

As someone else said. We may be an at-will state, but we do have anti-retaliation and bullying laws. If this harmless question got you harrassed and fired, after 25 years, it could have a case. Even more so if you were not so far away from retirement.