I am a law school graduate. What I offer is mere information, not to be construed as forming an attorney client relationship.
Can happen and does happen. If you live in an at will state, employers can do pretty much anything as far as job security or lack thereof is concerned. Read about it at the freeadvice.com MAIN HEADING ENTITLED EMPLOYMENT LAW.
Check your state law to make sure special circumstances or limitations do not or do exist. To do this, go to the freeadvice.com homepage. Click on State Laws. Click on State Statutes. Click on your state and then look under Labor Code or Employer-Employee Code.