Peggy, the markings look very similar to 'Amber Sunset' but from what I've read the coloring is slightly different.
Becky, it very possibly could have been a bonus plant, although usually I make notes in my gardening notebook about which bonus plants I've received and 'Chamonix' is not among those notes. (Then again, some of my gardening files/info were lost during one of my moves.)
I think I've decided for now -- after looking at many many photos and descriptions -- that it must be 'Chamonix.' Thank you so much for your help, all. I love this website, and this forum!