incomplete spay?

my cat is an indoor cat and was spayed last November. She did go through one heat due to me thinking she was younger than she was ( she is a small cat). Well a few days ago she started displaying heat behaviors. calling, assuming the mating position, etc. I called the clinic that spayed her and I will hear form the vet on monday.
I had never heard of this and have had many cats, always spayed or nuetered. The surgery to correct this is much more invasive, it is an exploratory surgery. Poor baby, but I understand, to my horror, ( have never dealt with a cat in heat before and have never allowed any to breed ) that she could keep cycling on and off all season since she won't conceive. This looks like it is so stressful for her and my hubby is not very tolerant of the noise. We are all losing a lot of sleep around here.
any advise would be appreciated, thanks Diane.

I would definitely have the vet check her out!! Some cats who are spayed after many cycles sometimes do this in a sort of psychological manner (with less noise) but there sounds like something may be wrong here. Maybe an ovary was left in or some organ that allows her to think she needs to be calling? I am glad you called your vet - and if that does not help, get a 2nd opinion!!

Can it create aggression by other cats in the same house??