Chris, I don't know if this will help ...I had the same issue, drove me nuts ( I am so meticulous about my equipment) . I actually pre soaked the spot with "Resolve" then I used a mild soap and water solution.  It came up ok but has never quite looked the same .  You can still see the once bright white has a dullness to it.  I wish I had tried an enzyme cleaner instead. 

Good Luck 

Paul ... thanks for sharing your experience.  It drives me nuts too.

I bought some Oxyclean powder and mixed up a fairly thick paste.  I wet the entire white area of the affected part of the bag and mixed up some Oxyclean to the consistency of paste.  I applied the paste directly to the spots and let sit for about 10 mins.  After the 10 mins, I blotted off the Oxyclean with a water soaked white towel.  When I thought I had removed the initial coating of paste, I then mixed up a spray solution of the Oxyclean and sprayed the entire area of white hoping that this would help blend the white better.  After several wet towel rinses, I let the bag dry over night.  The next morning the stains were gone and the entire white area that I worked on was bright white again!  YES!

I tried not to get the Oxyclean on either the black or red as I did not know what would happen.  This seemed to work very well on this material and now I am comfortable with cleaning the rest of the white areas of the bag.  It definitely took some time but it appears to be well worth it.  I may also apply 3M Scotch Guard to the bag when I get it all cleaned and maybe this will help prevent this from happening again.  It worked for me! 

Chris, What a Great Idea on the Oxyclean !  I never even gave it a thought and I have both the powder and the spray.  I am going to try it tonight and see how it works.  So Thank You for the tip.  Appreciate the conversation.