Can a spayed female exhibit symptoms of heat?

Hello! We adopted Isobel here in Los Angeles about 2 months ago. Everything has been going great, and then the last few days she has been acting as if she is in heat. She is approximately 2.5 years old and we were told she was spayed. The last few days, she spends several hours each day howling, prowling, being overly affectionate with us and just acting generally strange. She doesn't seem to be ill or injured in any way. Is it possible for a spayed cat to have "phantom heat" ? I've had some post-hysterectomy women tell me they still get PMS sometimes. Any thoughts? Thanks!

They can if some part of the ovaries were left inside. This can happen when the surgeon has a lot of surgeries scheduled. They can do a blood test to test estrogen levels to see if they got everything. Then it is an exploratory surgery to remove the remainder