This cannot possibly be related to the update.
The couatl64_MSFS.exe in version 2.8.8 is the same as version 2.8.7, something you can verify yourself by checking the date of the Digital Signature in the .exe Properties. Opposite to a normal file date/time, the date of the Digital Signature can't be forged or wrong, and you can see, it dates November 17th, that is 3 days before 2.8.7 came out.
Of course, as usual after any error report, I always verify what is being reported, so I tried a refueling (from Simbrief) with the PMDG 737-800 right now, and it worked perfectly fine.
For good measure, I tried twice in a row, no issues.
So no, it doesn't seem to be a problem of the update, it was just a coincidence but, since you haven't posted any error log or said if the simulator crashed too, it's difficult to say more.