When I buy potato chips, I do usually eat all the contents of the bag. I don't eat the bag itself.
Those whose diets are lower in fat will often have some oily leakage when they have a sudden large increase in fat intake. Those who've suffered injury to the anal sphincter will occasionally have a small amount of bowel leakage.
If either of these are a regular problem, you probably need to see the doctor. There may be a more serious underlying condition, one whose first symptoms include anal leakage.