Here's a perhaps strange question for you. Can running cause weight gain?

I know it sounds crazy, as most runners I know lose weight. I began running about a year ago, but now run 2 miles 3 days a week. I walk the other days. I have put on about 7 pounds and can't get them off again. I used to be able to stay OP for a few days and knock off some pounds, but it's not happening this time.
Some thoughts:
--I'm menopausal, so I think my whole body is changing (52 years old)
--I may be doing mind tricks and think I can eat more if I'm running
--I'm more muscular, but that shouldn't matter, should it? A pound of muscle equals a pound of fat, i.e. it's the same weight.
Anyone, especially Mrs. Jim, have any ideas?