Calling in sick to Kroger during 90 day period?

Hi, I was hired at Kroger on July 6th. So far, I have never missed a shift and I was late once by just a few minutes. I had dinner earlier and I believe I have food poisoning -- so much so that I was sent home from my 2nd job tonight. I know Kroger has a 90 day probation period where you can't do anything wrong. I know I have to call the store 1 hour in advance if I cannot be there. My question is can they legally fire me because I'm calling out properly during my probation period?