I don't think its spite like we humans think - but as stumpy said he could be marking his territory especially if he's not fixed yet, asserting his Alpha status (again as stumpy said) or having some separation anxiety. All of this can be solved by getting him a crate - the size is important....big enough to stand up, lay down stretched out, turn around BUT not large to the point, he could pee/pooh in the corner. Dogs won't pee/pooh in their crate unless of course they're sick.

If he was trained on puppy pads, he may also think this is his pad or perhaps he peed on this a while ago and dogs/cats will pee where they've gone before. If you get to where you're thinking he spiteful or being bad, this won't be good for your bonding. Dogs especially strive to please, so he's not calculating ways to bother you lol. Get him a crate and this will solve the problem - don't leave him for longer than 3 hours tops though. Get him neutered as well.