Possible they smelled the sweat from your hands on the cameras.... I have had deer, especially does, also key in on my cameras. Some of those were cameras that had the faintest audible "click", others had absolutely zero noise or other ways the deer should have picked them up. When I can remember to, I take gloves and wear them when swapping cards and batteries. When I set up mock scrapes at cameras, I go in as scent free as possible.
Last year was my second year using a cell cam, no checking/swapping cards didn't pay attention to deer keying in on the camera after placing it, but will try to remember to this year.