Is it possible that she could be going through a mini-molt? In that case you would probably see some feathers under her roosting area, and thin spots in her feathering. She may also be reacting to a change in the weather. I would not worry too much if she seems healthy--my chickens did not lay for 2 months, now most are laying well.
My girls have all slowed down in the past week or so. . . don't know if it is stress from having added to new kids to the flock, or if they are just taking a break. . . but they have been "superachieving" for too long now. . . they probably need a break. . .