Well, the change in behavior seems to date approximately to 2 cage
cleanings ago. There were a couple of minor changes I made: 1) I
starting using this "Carefresh Ultra" litter, instead of the regular
"Carefresh" brand. It looks the same to me, but it's white (the old bag
ran out, and I picked up this bag of litter). 2) I added a section of
tubing to her cage -- just a little loop to give her more space to
crawl. I didn't think the loop addition met with much approval (I never
see her in it), but when I hide treats in the loop they always seem to
disappear, so she must be using it when I'm not watching
These 2 things couldn't result in a dramatic change in behavior, could
they? Arrghhh, stupid rodent

I picked up several bags of that litter
so I wouldn't have to go back to the store soon (hamster food is easily
found in the supermarket, but "Carefresh" litter is a bit more out of
the way).
Here's another odd recent behavioral change. You all know how hamsters
pick a spot to build a nest, and this nest location can change on a
whim. Well about 4 weeks ago, Pumpkin has decided that the wheel was
the ideal place for a nest. Now the wheel (it's one of those SAM
enclosed side add-ons) is completely stuffed with TP and a food stash.
But she would still try to run in it, with the food rattling around and
all the TP continually knocking into her!