As long as the heading makes it clear what it's about, and it has something to do with travel or miles, then I think it's fine here. I don't get to some of the other boards that often, so for example when Atlanta/New York tickets were on sale for $30 each way, I never would have seen it if it wasn't here.
While I think moderation is a good thing, I think it's best in moderation.
If the topic is clear, and it's a close fit, then who cares, just don't read it if you are not interested in it.