Christmas Cactus drooping..?

My Christmas cactus - which was kept out on my porch this summer - was full of blooms when I brought it in. It is in moderate light, there hasn't been too much of a change in it's microclimate - BUT - the green stems are drooping. I thought it was because it was too dry - so I watered it, only a bit...does anyone have a clue as to what is going on. It belonged to my Mom and I'd really be sad if I killed it.