I'm currently in the middle of this problem too. I've never even seen E85 gas anywhere in Manitoba, so I certainly haven't put any in, but after my last tank from Superstore (regular grade) I got P0172 and P0175 with freeze frame data showing alcohol content over 75%. That was on the way home from an errand right after filling up. It eventually settled at 45.5%, and the check engine light would keep coming back pretty often. Too bad because we had a nasty cold snap around Christmas, and a CEL disables remote start.
Fast forward to today where I finally emptied that tank, went to Shell and filled with premium 91 octane zero ethanol, hoping it was just a bad batch of gas. I then headed for the highway and went far a drive, about 40km. Watching the alcohol content bounce around on my BlueDriver, it finally settled at 27.5%, and the short and long term fuel trims are still just as bad as before. I'm sure I'll see a CEL in the next day or two.
I just hate to go pay the dealer a ridiculous amount of money to reset the fuel trims just because I don't have a Tech 2. Depending on what they want to charge, it may be worth it to get an Alibaba Tech 2 and then I'll have something to keep after.
I'm glad to hear that you're still running problem free after your dealer reset.
If anybody is interested, I've attached the PDF of the freeze frame report.