I had wondered about this too, I filled up this weekend at my local truck stop, it's a Cenex, and I noticed this issue this last weekend, but I did alot of running around over the weekend and needed to fill up last night before I left work to go home and I filled up at the Shell truck stop next to my work, so between going home last night and back to work today I have over 80 miles on this tank of fuel, and it still sounds the same, and neither place has posted that they are blending yet so I'm like hmmm maybe not that, I dunno.