It's about honesty, plain and simple.....what would you do if you were overcharged? Complain........
It happens elsewhere and great shall your reward be. Airlines for example, I once had fabulous service overnight from Nigeria to London in Bus Class....I'll ignore the details but I sent a letter in to them to thank the staff. A few months later, I went Lagos to London to Jeddah in winter with them and it was chaos, I ended up in BXL first and then made it to Gatwick, my luggage in Frankfurt, a flight next day London to Jeddah.
They paid for the hotel and would have settled on quite a wardrobe; I was happy with a 1st class male bag, socks, underpants and shirts to cover the anticipated two extra days that it would take to reunite me with my case in Jeddah.
I checked in and I had been upgraded to 1st for the flight out; I found out that a positive letter offsets 8-10 negatives that they receive and it bumped you up the 'appreciation' list. Bet it hasn't changed that much...
This is the same - you should be honest, your rewards may come later, next time that you check in, a bottle of complimentary bubbles perhaps?