what kind of food do you feed them? depending on what kind and the main ingredients, build up can form in the kidneys causing urinary tract infections. Was it a lot of urine or did it have any kind of tint to it? Has he been going more often but urinating less in the litter box? cats don't really have the mental ability to reason so they don't necessarily hold a "grudge" towards you. At least not to the point where he can think "she did this to me earlier, so im going to pee on her clothes". y'know what I mean? Theyre much more simple minded than that lol. Its basically, like perna said, trying to get your attention for something or he's sick. im going to say that since it was on your clothes that had not been washed yet, it was to get your attention. He chose something that smells like you knowing you would find it. If it were something like a UTI it would be constant urinating on the carpet, leaking when he runs or you pick him up etc... But always go to the vet to make sure.