I 100% agree and imo this is NOT normal.
Some cats get upset stomachs more frequently than others. When this happens they may shun their food; this happens to my cat every once in a while as well. But 3 days is too long. In addition, there are several reasons besides upset stomach that may cause a cat to shun food.
My rule is 24 hours of not eating equals a problem, so given that this is 3 days, it's a problem. Please take your cat to the vet.