How much sun does yours get compared to hers? Apparently some red maples may not turn as red when they don't get enough sunlight. I have ordinary red maples and many of them turn yellow ... and they are in a fair amount of shade. The ones in full sun have more red color.

I don't think that's it. Both get about the same. They are both out in the open and get at least 6 hrs midday sun.
You just made me think about another possibility however. Maybe I don't have a real October Glory; maybe it's some other hybrid or even an ordinary red maple. I bought it from a wholesale grower who sells mostly to builders, and it was unlabeled. "All those trees over there in that row are October Glory, the ones in the next row are Red Sunset, and in the next row are ..." you get the picture. It seems like it would be easy to get them mixed up. I seem to remember colored ribbons tied on them for identification.

Yes, it is possible you got one that wasn't a true cultivar. But it is a little curious that it was red last year. Of course even non-cultivars can have good color, after all that is how they found the first "good" one anyway. But it is odd that the two years could be so different!

I have hundreds of seedlings and in the fall some of them are just as screaming red as any traffic light. Course they only have one or two sets of leaves on them! And I wonder if I left them, would they grow up to be that red every year ... but then I yank them out anyway.

Let us know if you find anything out (if you contact a nursery or the extension service or Walter Reeves).

Nancy, I've encountered the same thing. I planted two October Glory maples in the summer of 2006. In Fall of 2006 and 2007 they were both red. This year, one is red and the other looks just like a sugar maple.

They're both very pretty but I'm not sure what to make of it!

Franny

The fall colors of Maples are genetically determined, siting, soil, moisture, nutrients cannot change that.
October Glory was selected from a seedling pool of Acer rubrum,var. columnare,as having the following attributes: a mounded habit, brilliant red fall foliage color, that persisted several weeks after other Red Maples had lost their leaves.
As long as it is asexually reproduced, i.e.,bud graft*, rooted stem cuttings, tissue culture, it will retain those features.
*Bud grafting is seldom used today, as the results weren't always predictable. The rootstock didn't cooperate, in some cases, to produce true-to-name cultivars.
You may have received one of those or most likely, a sexually (seed) produced tree, which can be quite variable.
October Glory was patented in 1961 and the patent expired in 1981, but some nurseries still collect royalties on sale of the trees and others may be mistakenly producing them by seed to avoid paying royalties, which haven't been required for almost 27 years! Besides, seed is easier!
Rb