Yes, deer have been known to do that. Sometimes they chomp the entire plant off, just leaving the roots in the ground. At any rate, don't pull them out. There's a very good chance they'll recover, although it might take some time.
I don't think sempervivum are normally a favorite choice for deer to eat, but this time of year when other food is scarce, they will eat them. My recommendation is to get some Plantskydd and spray it on your plants. I have deer problems when the tulips and lilies come up, and Plantskydd works great to repel them. It also works on little critters like chipmunks and rabbits too.
http://www.plantskydd.com/fore...
I hope they didn't eat them all.
