Someone posted this: http://imgur.com/a/m21KG
I think it's important to note that something as simple as an inverted symbol COULD be an oversight and nothing more, but airships are definitely something more readily associated with the Midwestern branch, since it's absolutely confirmed they used them, which isn't the case for the Eastern branch as I recall.
What's strange though is the name Prydwen then, as that seems like a reference to the Eastern branch, no? (Lyon's Pride)