I found the same thing with my baby Martin, so I don't think it's pecular to your guitar. Lower-pressure capos (as suggested) did help some. It may be partly a "feature" of baby Martins, though I found it happened with a little Taylor I tried for comparison. I don't have as much trouble with my Larrivee parlors, but they are a bit bigger.

Good luck, and let us know if you find a great solution!

JudyB