Just be thankful it wasn't 1985 Austrian late-harvest (many different vintners); they were adding diethylene glycol to sweeten them. Which it did, along with causing death and blindness (if in large enough quantity). The wine industry has always been full of quirky behaviour.

Now, rather ironically in some ways the 1991 red Corton is superior to the 1990 vintage (after aging), at least for some producers, and with surprisingly marked style differences between the vintages. It is the white that has a big difference between 1991 and 1990. The 1991 was very closed for its first 5 years but has opened up beautifully with age, while the 1990 was very forward. So you might actually have gotten a better wine.