Seth's emotions tend to change more often than the weather these days, so this is really par for the course. It's probably some sort of reaction to grief or trauma or something, but Seth wouldn't really know, he's just kind of along for the ride.

"Yeah, how dare you go and get yourself killed in front of him?" Seth jokes quietly, morbid humour to try to adjust to actually talking about it. At least his joke is lighter now, not just a bitter effort to push things aside.

"But yeah, he..." he starts, nodding a little sadly. "We weren't doing too great." Seth both saw and realised how terrible it must've been for Johnny, but unfortunately he was in no state to help - he still isn't. He just has to hope that Johnny's getting his support elsewhere.