Who is to blame for worms in dry dog food?

I found what are apparently meal worms in my dog's dry dog food. I am completely disgusted! The vet says it is harmless to dogs thank God. My problem now is within the last 6 months I have changed both my brand of food and the store I buy it from. Now I'm wondering if I blame the dog food company and switch brands of food again (I was so happy with the food until this happened) or blame the food store for improper storage and buy the same brand from another store? Do I do both, do I do nothing? Where do you think the problem originated? By the way the food was Blue Buffalo chicken & brown rice.