The specifics of Aether Sickness, such as how it is caused, isn't really explained. It is heavily implied that you're not from around here - as in, not remotely from any of the city states that we know. But you are specifically able to say that this is not your first time to X city state upon your conversation with one of the merchant brothers. The narrative door is left wide open for you to be arriving from anywhere on Hydaelyn, really. Regardless of that, the merchant does seem to assume that you have been away from the realm for long enough to require some explanation even if you do tell him that you've been to the city you are approaching before. The text is just ambiguous enough to leave some wiggle room for your character to be from "around here," even though the tutorial information provided by our merchant companion suggests that he, at least, believes that we are ignorant about how adventuring works in these parts.

I'm in the same situation as Enkidoh, having played a THM until about lvl 35 and having cleared up to "Together We Stand" in the main scenario and up to Ifrit in the 7th Umbral Era story. Nobody remembers anything I did, even though I remind people of The Warriors of Light. I didn't complete the Lunar Transmitter mission, deemed the sub not worth paying for in the reconstruction period - even though I bought the 3 months for the sub discount when it was offered with the expectation that this game would eventually be worth paying for again. Still, it would have been nice to have been remembered by any one of Thancred, F'lhaminn, or Momodi. Technical limitations, I suppose. That, and it would have been quite difficult for the devs to program vastly different dialogue for those who were at Cartenau and therefore forgotten and those who were not and therefore should have been remembered. Thus, it seems that those of us who only got so far in 1.0 were forgotten in the more mundane fashion.