Hello and welcome ... My name is XXXXX XXXXX I am an experienced small animal veterinary surgeon, I will be very pleased to work with you today and will try my best to answer your question to your satisfaction.
This is something I have encountered now and again in my career, it is rare though. You see during spaying the ovaries are sometimes traumatised but this is no problem as they are being removed anyway, this leads to a surge in female hormones and this in turn can make the dog appear to come into season and be attractive to male dogs.
This is not a serious situation as the residual hormones will decline on their own over a on eweek to ten day period and then things will settle down, and never recur again
There is unfortunately no treatment though, all you can do is to wait I am afraid ...