Tuna Microeconomics

My price of tuna went up, so now I eat more of it. How does that work?

I used to pay $0.75/can for tuna at Western Beef. That was the chunk light variety in water, though I'm not very particular. Then Western Beef raised the price of its store brand to $1. At first, I cut back on my tuna consumption, but now I see tuna on sale at every grocery store for $1. It's frequently higher, but with all my grocery stores and all the brands of tuna, I can always find it somewhere for $1. Now I don't have to make a special trip to Western Beef, so I tend to buy tuna frequently and I'm spending 33% more per tuna-unit.