No, sarcasim is when you say something that isn't true such as "that dive was completely safe, really". What that was (or at least what that sounded like) was laughing off a dangerous situation. When I first read that, it reminded me of the attitudes of a teenager (while laughing: "man, we almost ran right into that embankment, that would have sucked").
If he meant it some other way (and text is notorius for being mis-interpreted), I apologize. If he didn't, well, my original comment stands.
If he meant it some other way (and text is notorius for being mis-interpreted), I apologize. If he didn't, well, my original comment stands.