neutered cat still wanting to mate

Hello
my male kitten was fixed a year ago and was fine now he has started humping our quilt on the bed and crying is he frustrated or did the fix not work. should we go back to the
same vet, we called and they said its was unusual, and could we take a movie of him ???????? he is a maine coon we love him!
our last one lived to be 24 1/2 years old!

Answer by Kate
are you sure it is hunping behavior? I mean it would be very unusal as his hormones should not be there that would encourage him to do this. It may be something else like kitten behavior like neading mums tum or even a stress related behavior, does he have enougfh to keep him entertained during the day?
If it is mating behavior then yes take him back to the vets in case their is some other hormonal thing ahppening that may cause similar behavior.
Best wishes