Costco just announced big news, again.Costco Wholesale (COST 1.70%) is a pretty straightforward retail stock. It doesn't come with the glitz and glamor of tech, and it's been a steady market-beating stock over its decades on the market. But the past few months have been a nonstop, action-packed story for the warehouse giant.The most recent announcement is that it's cracking down on non-members coming into the store. Let's see what's been happening at Costco and whether or not this is something to worry abou ...