Less MPG after fuel filter replacement?

Because I live in the rust belt and the previous owner never changed the fuel filter the front banjo bolt was froze and I could not break it loose. After many cuse words and a can of PB I gave up on getting my fuel filter off and took it to my local mechanic. He put on the Purolator filter I bought from advanced and for the last 6 fill ups I have noticed a decrease in MPG. I track my millage with a Iphone app and I went from the mid to high 18's to 17.5-18 over the past 6 fill ups. I drive a lot for work!

Any ideas?? Could it be the change in weather?? Could slightly more fuel be flowing easier through the new filter??

No major concern as it runs a bit smoother now, just curious what others think.

 

curious..but it could be that we are on winter blend gas now

 

I had noticed a slight decline prior to changing it, it was only noticeable if I looked at it on a line graph.

 

probably winter gas