Leo is humping my newly spayed Bella

[Specsy]

So, I had Bella spayed on Monday morning, she was not in heat. I had waited until her 2nd birthday (7 June) and made an appointment and Monday was the closest so I took her in then. On the 2nd day after Bella's spay, Leo is suddenly wanting to hump her. He sniffs her (as if she were on heat) and attempts to mount her. Bella is isolated at the moment, I just will not risk torn stitches. However, any idea why on earth he is doing this? He is being a real PITA. He has NEVER attempted to hump Bella before, like ever.

Edited because of lack of coffee mistakes...

[YodelDogs]

She smells like "hospital" instead of her regular self and she isn't giving off the same amount of hormones she did before. He is probably just confused and should settle down soon.

[Specsy]

Thank you so much for this information. I have another male at home right now, am I going to have the same problem when he goes to get neutered? Is it possible? It's slightly annoying, can I do anything to alleviate things?