I would call your vet and tell them what is going on and see what they think.They can bleed some after being fixed.If she is still doing that after a few more days then i would get her checked.My peke did the same thing for over a week and they told me that as long as she wasnt running a fever and was acting fine then she was fine.Good luck and take care.
I week ago is not long. If I were you I would call your vet, or the vet who did the surgery, and ask their advice. It won't be a heat cycle, as her ovaries will have been removed, but it could be a slight complication from her surgery. Don't hesitate to ask the vet for advice.