As long as she didn't lick her fingers, then I really don't see too much of a problem with this - only that she shouldn't have done it in front of customers.

I've worked in the food industry for 7 years. There's no getting around it - the workers steal food. Too many times to count I have popped a cookie, taste of ice cream, hunk of bread or bagel into my mouth while I was working. But I always took care to only touch what I was eating, I didn't lick my fingers, and I didn't eat in front of customers unless I was on my break.

It was only two fries. Not a handful. I don't see how that's cheating the customer. Unless you're ridiculously OCD and count each fry in your box?

Calm down and realize that food industry workers gotta eat too and sometimes that means sneaking a fry.