My cat hisses while playing.
My cat loves me and my family very much, even if he doesn't want to be picked up or sleep with us. He trusts us, always sits next to us, preferring our company rather than solitude. Even if he doesn't sleep in a bed with a person, he always sleeps in an armchair next to the bed. But even when you pick him up, he doesn't resist.
He has never been aggressive towards me and my family (although he is afraid and dislikes most strangers, hides and hisses aggressively if someone else approaches him, maybe even scratches hardly).
But he has one feature, and I don't understand if it's aggression.
He hisses while playing. It doesn't happen often, maybe once or twice per play, even if I play with him for an hour. Even if he is playing by himself with a toy, he may hiss. During hissing, he does not flatten his ears, does not show aggression, just hisses some times during the game.
I tried to find information about this, but everywhere it's just that cats hiss only as a sign of aggression.