At will employment (which is most likely your case) means you can quit at any time for any reason.
So the employer can fire an individual at any time, for any reason as well but it must be within the law.
Though for some terminations you could collect unemployment pretty easily since the reasoning might be questionable, though unemployment is dealt with on a case to case basis.
All this being said you would most likely be protected under the "Americans with Disabilities Act" (if you are in the United States) and probably under some state specific employment law.
Bottomline: Probably not and I wouldn't worry about it if you have been a good employee up to this recent problem (i.e. don't have excessive lateness, take excessive time off without a legitimate reason, etc.)
