My cat behaved very strangely on Sat - not towards me but just running and growling. Took him to vet where he behaved very well - nothing medically wrong. Brough him home and he just continued to growl, spit and run around. Eventually had to place him overnight in his cat box and next morning it was like it never happened and has not re occurred. I have cat nip growing in the garden and he is sometimes aggressive towards that. Would it have been something he ate?:confused: