Did I just got scammed by a foreign trader?

[pannu]

Potential spoiler alert (revealed already in the subject)!

Is this a game mechanic or a bug?

I met a bunch of foreign traders. Traded a decent elk fur to 9 superior broadhead arrows. After the trade I looked at my inventory, it shows 12 "regular" arrows (around 3 arrows I got already + the 9 new; also had various bonehead arrows). I wanted to ask this "Dagowin" (if that is his real name) a few questions, but of course he does not know what I am talking about. Now he is selling regular arrows.

Has this happened to the others? Did you outright stab the bastard, or perhaps offered tainted meat to celebrate your friendship?

My character happens to have max intelligence, this is why noticed the scam immediately!

(mods, consider moving this topic to a corresponding subforum)