Did Karen almost die in Goodfellas?

Let's go over exactly what happens in this scene again:

Karen brings something to Jimmy and Jimmy asks how Henry's doing. He gives kind of a flippant response to her answer, then looks down and is silent for a little bit. They have a quick conversation, he gives Karen a couple thousand dollars to put in her pocket, kisses her, and then offers her some dresses. She says she'll take them so he directs her to a store on a corner, kisses her, and says he'll see her later. He stands outside the place where they were, watching her walk down and directing her instead of coming with her. At one point he looks behind him quickly. Karen sees two guys lifting boxes behind a gate, then they pause and look at her. She stares for about thirty seconds and turns around and runs back to her car to drive away. Jimmy sounds upset and frustrated and says "no, no no no, it's in there! Right in there! Oh come on!" And then looks mad and stalks around after she drives off.

So was Jimmy going to have Karen killed by the two men behind the gate, or was Karen just super-paranoid? If so, what motive does he have, and if not, how can this scene be explained?