I'm not a breeder; perhaps one of our veteran breeders will come through here and see this early this morning... but in the meantime, I'll give what advice I can (which consists mostly of asking questions I suspect whoever can be more helpful will want the answers to).
First of all, are you 100% sure she's bleeding and it wasn't red urine? Secondly, how much blood are we talking about? Is this her first litter and if not, when was her most recent litter born and has she ever had previous complications? Age/breed?
Personally, I would call your vet's office when they open and ask if you could speak to your veterinarian over the phone. They probably don't come in until 8-9 even if the clinic opens earlier than that but you can leave a message and hopefully get a call back before the vet gets busy with appointments. Explain the situation and try to get them to tell you what the potential causes are (perhaps insisting that you have work or something and can't bring the rabbit in today unless it's a life-threatening emergency)... some vets are cooler than others about advice over the phone, so it may or may not work (it definitely helps if they've met you in person before and have seen that you've got a lot of experience with rabbits)... but with a little luck, you can get a good idea of the potential causes so that you can do some research and weigh out for yourself whether or not you feel she needs to actually go see the vet.
