I was terminated with an employment contract, no reprimands in file, possible in an at will state?

If I have a signed employment contract with office can they still just fire you willy nilly?

I worked for a dental office for 11 months and was terminated yesterday for, as the Dr. put it "not being a good fit" When asked why, the wife said I didn't want to work the front office and I was too defensive. (I was hired to be a back office assistant but helped out the front when ever there was down time.

This Dr/wife team is something else. Manuals for everything, S.O.P. sheets for everything that is done and they change frequently.

When I was hired I signed an employment contract which stated the reasons for termination (stealing, talking about salarys, copying keys...the obvious) For other offenses the contract states that 1st offense would be a verbal warning (I received one) and then the 2nd and 3rd would be a written warning in your file and the 4th would be termination. I have never received anything but the one verbal warning for being defensive when the Dr. accused me of being lazy. (the Dr. is very hard to work for and treats his assistants like dirt) Other employees have been "written up" and have signed such write ups.

I took 3 days off work with pneumonia. In my contract, it states I could have 4 "personal days" after my 90 day trial period. I was at 11 months and never used them. When asked, I was told that they changed the policy to 1 year instead of 90 days.

A month ago, I received a letter telling me that they enjoyed working with me and was happy I was a team member along with new contract changes which didn't mention personal days.

Geesh, sorry so long...