My hunch is that maybe the proportion of water dissolved in the fuel (there always is some) had not somehow been confirmed. Possibly as simple as a requirement to sample test it every 24 hours, and it was noticed it hadn't been tested for 25 hours - that is, it was a paperwork issue rather than anything specific. Ending up being described by Chinese Whispers as 'dodgy fuel'

However, should not be a "not my fault". It's an airline responsibility to get everything right.