Why does my cat acting different?

[Anonymous]

Have 2 year old cats. Both are spayed and neutered and belong to the same litter. They were buddies but sometimes fought, mostly out of fun. In a last few days, the male cat is looking for opportunities to chase and jump over the female cat and bite her. She hisses back and I have to clap my hands to scare him away. This is becoming more frequent. They had their vet visit 3 weeks ago and everything was well. They took rabies and distempering shots.
What could be wrong with the male cat?

[Anonymous]

OP here.
* Typo in the subject line: Why "is" my cat acting different?

[Anonymous]

Our cats do that too. The male cat is showing that he is the boss. They might be bored, brush them or give them some things to play with.

[Anonymous]

I'm so glad the grammar police is on patrol this morning.