I absolutely would bring it to the manager's attention. You don't have to reveal yourself as a shopper when you do. If I am shopping a restaurant and find blood in my food, I'll complain just like any normal customer. I'll then put it in my report. The beauty of it is, as a shopper, you know your complaint will go above the store's management.
I was shopping a bar last week and the beer tap was not working correctly - causing the beer to come out as 90% foam and wasting about 1/2 what was poured. Overhearing the bartenders voice their frustration, I learned that the problem had been going on for two months and that they had voiced concern about the amount of waste on a couple of occasions, but were blown off. I have a hunch that the problem will be fixed by next week after I reported it, in detail. It's not as serious as a health violation, but should get the company's attention just the same.
Hard work builds character and homework is good for your soul.