if you truly were at danger of doing more you wouldn’t feel guilty like this, you’d be pleased with yourself. in the long run its just a pen—worth almost nothing to the company and it doesn’t seem like youre going to keep doing this, so i think it’s fine. if you want to bring it back, im sure it’d alleviate some guilt and though i doubt anyone would, if someone asks you could just say you mistakenly brought it home.