Hi Loretta,
Thanks for those suggestions. I've turned on the door alarm but haven't heard it go off. Last weekend I took the bottom access panel off from the back of the refrigerator. The fan seemed to be working fine but there was a layer of dust on it so I cleaned that off. On the coils that went under the fan there was some water that I dried up using a paper towel. Since that time (it's been 3 days), the problem hasn't repeated itself. Not sure if I'm just lucky or if I've bought myself some time.