Cats spray whether they've been neutered or not. Just to dispell that myth......

Yup, agree with the stress theory. Follow all of the above advice, plus extra chin scratchings and cuddles, but don't, whatever you do, clean up the mess with a chlorine based cleaner (i.e. bleach). As far as a cat's concerned that's just like the biggest cat in the world peeing in the corner and they will do their best to compete......

Oh and extra chocolate for you Pixie.... :0)