Was this the correct move in this situation? Maybe there is a weakness in the corner, but is this the best way to protect it? Something makes me feel weird about playing this move as black.

It turns a sente-by-white endgame play at T4 into a gote-by-white play. It precludes all possible invasions. When you are up by 20+ points, it is best to play safe.

BTW, I think that the clamp at S2 would become a ko if black did not play something.

I guess it just seems like a weird shape to me. I don't have any rationale, really, for thinking that it is wrong... Except maybe that it makes some of the other stones look unnecessary (maybe R5, for example).

Okay. Center isn't that big.

We already know how this sequence ends.

20 points ahead.

I'd like to ignore it but that's impossible. I have to count again for the game to see whatsup.