I don't normally age and if the injury is physical, it heals.

(read: he doesn't care that much. he'd definitely be dead by now if he were any normal, but he isn't. it's fine.

iwaizumi might notice all the care and love he has as he tends to the pipe, removing all residue as he takes it apart.)

It's... Emotional rather than physical, I suppose. You'd find it very out of place had you met me a few decades ago.