Let's not over look Kroger chains, It's the countries second largest supermarket chain by revenue. Second largest retailer behind Wallmart. Fifth largest retailer in the world. It has 2625 stores as of 2013. My wife was at a local store,the shelves that would have I were empty, the I was moved to an end cap as if they were getting rid of it.
I work for a major supplier to Costco. Most vendors don't go national immediately. Costco has distinct regions and many products are given additional regions based on performance. Performance can include delivery, sales, quality, etc. Costco even goes to the extent of doing "social audits" - which are designed to make sure that factories are safe and employees of the factory's are treated correctly. If a vendor excels in these KPI's then a product can go national very quickly.
If the mystery retailer is indeed Costco, then this is a great opportunity for MINE to make a large footprint quickly if they perform as expected.