I have an Atlas good luck quart jar that is 8" tall to top of lid. A customer has a quart that is only 7" tall i have had a number of these that were all 8". Were they made in both sizes? Or is hers a reproduction?
One need only glace at a copy of the RED BOOK FOR FRUIT JARS to see that there are so many mold variants for common jars. The book really is a necessity for a collector of jars.
I have been a bottle collector for many years but am by no means a jar expert. Not sure if the Good Luck jars were reproduced or not but my hunch is that you have found a mold variant.
Hope this helps.