Klopp did not actually say he's done as a manager. He said *as of today* he feels like he's done as a manager, but he also said that in a few months' time he might have a different view.
Having just been on the first prolonged real vacation with real relaxation in a long time it's hard to blame him for feeling that way, but let's be real here, these remarks are those of someone who's deeply aware of the potential that the 'itch' comes back when he sits on his couch in November and watches football matches on TV. This is a guy who is on record of having said that he can't imagine life without working with a team on a daily basis.
I'm not saying he's definitely taking a job next summer, but if he did I also wouldn't be surprised.