A difference like that for a single tank can be for any # of reasons. I've had a few tanks like that. It's not worth sweating over.

Remember- the computer is calculating using the odometer and what it says the fuel flow has been, which may or may not be super accurate. Even Honda may slip up on a calibration now and again. A sudden temp swing, or who knows what, can affect accuracy.

Meanwhile, you are calculating using the odometer and what you think you actually put in the tank...based on a pump that may or may not be super accurate, and which will vary from fillup to fillup by some amount- depending on whether the tank 'burped' the vapor out or not, etc.

Several sources of error on both sides...it will be a rare instance when they cancel each other out and the final results match. Some might call it accidental. Point is, neither method will be 100% accurate 100% of the time. If you have a fairly consistent offset most of the time, you're doing pretty well.