Teleporting Hacker?

I wasn't sure where to write this...

But lately I've noticed a single character randomly popping in and out from a Gridanian Market Board.

I've taken a SS and noted the name down, but since I am not entirely sure if it IS a hack; I will not reveal the name.

Though from what I noticed, the player randomly pops up in front of MB then disappears in a few seconds or minutes. Even as I am writing this now, the player did this 3 times (to this point).

Okay so maybe I'm lagging and players are popping in an out, but this is not peak time for a N/A server (I'm in Japan).

Or maybe the player is farming a dungeon? (Similar to DD first room farm)?

What do you guys think? Am I simply overthinking this?

He could be farming a dungeon or have connexion issues, why not ask him? X)

It could also be someone's alt that's parked at the MB due to retainer there too (sending retainers out selling stuff, checking MB)
If you login to quick check something then logout it would appear as just appearing then vanishing