Hello and welcome to Just Answer. I am a licensed veterinarian and would be happy to answer your questions but need a little more information.
Was Maggie in heat (or due to be soon) around the time of the spay?
Is the bleeding excessive or a small amount?
Is it pure blood or bloody fluid? Have you seen her urinate and is the urine free of blood?
Thanks and I will respond when you reply.
Maggie was not in heat.
Small amount of blood
Well that is certainly not normal, but not necessarily a problem. I would first check with the vet that performed the surgery to ask about the condition of the uterus when it was removed. Since Maggie is two, it is possible the there were changes in it consistent with her possibly having an estrus cycle soon. In that case, the uterus becomes much more vascular and perhaps the stump that is left had some tissue that was already reacting to the changes in hormones that occurs during estrus (before the ovaries were removed). This would be expected to subside soon.
Another possibility is that it is coming from the bladder. If she has bladder irritation or infection, she could be passing blood or blood clots. I would not expect to see other post op bleeding unless there was a problem that has developed with her clotting ability.
I would follow up with your vet and keep an eye on it. If it is not resolving on it's own very soon, it definitely warrants further investigation. I hope that helps. Please let me know if you have any further questions.