Oregon's laws are a lot more permissive than Washington laws and that seems to be the way laws are evolving state to state. In both states medical marijuana patients can possess more pot and grow their own marijuana, so this comparison is focused only the laws that deal with recreational weed enthusiasts.
What makes the story particularly believable is the fact that Costco was founded in the Washington town of Kirkland, and that Costco is now the world's largest seller of Wine and Liquor with billions of dollars in revenue each year coming from alcohol related sales according to published reports.
Now that marijuana is moving toward national legalization, a new set of questions are emerging and states are doing their best to deal with past mistakes properly. A newly decided landmark Marijuana court case in the state of Connecticut may quickly become the example all other states follow when wrestling with questions about the best way to handle existing marijuana convictions in jurisdictions where the laws have now changed so that the exact same activity would now no longer warrant any kind of criminal penalty.