I found the info I had read.
to make melons taste sweeter, hold off watering a week or so before you expect to harvest the ripe fruit.
also...
melons need at least 90 - 100 days of hot weather to sweeten
Possible your seed would have been good ~ just not in this years growing season.
One source had recommended a plastic mulch to prevent the soil from absorbing too much moisture in the last week.
Worth the effort? I don't know...