It's not unusual at all. My IBS symptoms are present regardless of how or when I eat. Many folks, myself included, WAKE UP in pain and distress, after at least an 8 hour fast from food.
Eating CHANGES my symptoms. I abstain from food all day but I still have pain and discomfort. The difference is that at least the BM's are somewhat controllable. After I eat, all hell breaks lose! I may spend the entire evening in the bathroom with D or I may spend it on the couch with a heating pad on a gas-bloated, spasm-filled, snarling and twisting belly. Either way, there is always pain and discomfort.