Did you get 6k qualifying miles for that trip? It looks like MDW>LAS is around 3k miles. I just did a trip to Phoenix over the weekend. I got the normal qualifying miles but double 2.5x redeemable miles. I am 100k, so should have only been 1.5x redeemable. You have me curious now, so I will do the math and see if they gave me bonus qualifying miles instead.