According to the news release, the company has already tested the idea at their Hawthorne store. The experiment has provided mixed results from customers.
Explaining why the test is being done now, the company says they want to be ready in case state legislation, or local ordinances, are passed which ban plastic bags in retail stores. The company stated, "By beginning and testing this plan now – and getting your feedback early– we can make sure we have everything right before new legislation goes into effect. It’s also better to begin our efforts earlier before more local governments put more piecemeal rules in place."
Back in late January of this year, Senator Mark Haas introduced legislation to ban single-use plastic bags. (See: Plastic Bag Ban In Oregon? The article also has a link to the full text of the bill SB1009.)