All Sten did was finally notice how good-looking she was, now that her blankness wasn't the only thing he noticed, since she's wearing a limiter for the first time in Sten's presence. His imagination (and possibly the warp) has a tendency to take ideas and run with them in his head. Chances are pretty slim we end up with an Eisenhorn/Bequin style relationship.

PS: Sten still hates her.