Now, just hear me out here...
This scene ain't just a one off joke, it's hinting that something's going on in Skyloft. Something bad.
The fact that Sky is disappointed implies that every time they've had a visit from the postman he's had a letter from her. The reason this time there's no word isn't because she didn't write, but rather she couldn't write. I'm just saying the boys must have been in town for a while and Dink has been awfully quiet- sure he's been regenerating and all that, but maybe he's moving onto the next phase of his plan.
Maybe in a few chapters the boys will walk through the portal into a war-torn Skyloft destroyed to a level they didn't think Dink was capable of. Sky is freaking out, Warriors is having war flashbacks and everyone's worried about it being a multipronged attack on all their eras. Just a thought :)
Art credit @linkeduniverse
