She is probably craving fiber because the lack of hay can cause the digestive system to slow down. If her pellet amounts are limited to a small amount each day and you aren't feeding extra pellets or veggies to make up for the lack of hay, then it could also be that she is really hungry and that's why she's trying to nibble on things. If she isn't getting enough food to make up for the lack of hay, I would offer more of her usual veggies/greens and give a little bit more pellets, then first thing tomorrow you need to get her hay. If she wasn't inclined to chew on things before this, then once you get hay for her again it's likely to go back to normal.
You probably already realize this, but abruptly stopping hay when it's a normal part of your rabbits diet, isn't good and can actually lead to serious digestive illness developing. Fiber in hay helps stimulate a rabbits digestive movement. It keeps things flowing through there smoothly and helps prevent digestive blockages from occurring. Without enough fiber in a rabbits diet the digestive system slows down, can slow down too much and become stagnant, which can result in pathogenic bacteria developing. This can lead to things like bloat, toxic diarrhea, or a digestive blockage occurring. Rabbits tend to have a very sensitive digestive system, so it's important to keep that hay supply stocked so you don't run out again, as good quality grass hay is the best preventative for digestive problems in rabbits.
