I thought this was pretty funny when it happened, but it does smell like a bug.

Playing DA 1.80e.098 as a custom civ and went to trade with the Altarians. I don't remember exactly what I was offering, but I was asking for Soil Enhancement and New Propulsion Techniques. There were saying No. However, when I added Ion Drive to the list of what they were offering, they were suddenly quite pleased to make the trade.

Naturally I accepted, but it probably shouldn't have worked that way...