The indent seems to be deminishing on its own. After reading many other posts about indents, this seems common once the "force" has been removed.
I'm wondering if perhaps the bulkhead contracted due to the cold, sucking the hull in with it. The temps were pretty cold (-20C) when I first noticed this problem. Now that it is warming up (0C) the problem is going away. The problem is on the north, colder, side of the boat.
Another clue...the large piece of wood under the keel
cracked and split over the winter. I'm pretty sure the keel
is at least 1/2" lower than when she was hauled. This info was hidden beneath the snow until just recently. I checked all the pads, and there are no indents near any of them. Its a 6 pad cradle
I also must remind myself...the boat is almost 40 years old. Who knows what has happened over all that time.
Thank you for encouraging me to post a pic. Seeing that pic on my computer screen
has reminded me that I've got a great boat (and very shiny), and I'm going to be sailing her again really soon. I was so focused on the dent, that I forgot about all the other good stuff.
And finally, thank you to everyone who offered advice. It seems alot easier to tackle these issues when you don't feel so alone. In this case, the problem seems to have resolved itself. Of course I'll keep a good eye on it, just in case.