Can't trade currency items (with lvl >25)?

Today, I (Lvl 74) wanted to trade a skill gem for an Orb of Alchemy with a Lvl 36 player, but he said he couldn't place the orb in the trade window because it said something about requiring "lvl25".

Of course, I can't verify this, but he then tried dropping the orb outside town. In the screenshot below, you can see that he is Lvl 36 (so there shouldn't be any trading restrictions, right?) but I couldn't pick up the orb.

Is this a bug, or what is going on here?