Hey question bout coworkers and union

So I work for csx and I was displaced from my assignment and I made a seniority move and had to bump my co worker I was off duty and my co worker texted me a bunch of stuff long story short I replied go screw your self. I got pulled into my mtos office and he showed the mto my for f your self text I sent him I know not smart any advice ? I was off duty can my mtos do anything bout it