Gatsby vs. Tom Buchanan?

"They shook hands breifly, and a strained, unfamiliar look of embarassment came over Gatsby's face...I turned to Mr. Gatsby, but he was no longer there." pg 74

The above excerpt describes the event in which Nick sees Tom Buchanan at the same resturant that him and Gatsby are dining at. It really struck me when the "Great" Gatsby, so genuine and level-headed, gets nervous around Tom. At first I wondered if Gatsby was simply jealous of his demeanor or if they had a past run across with each other. Then, I remembered the point in the story where Meyer Wolfsheim tells Nick of Gatsby's "very careful" attitude about women, and that "he would never so much as look at his friend's wife." Considering the reoccurring theme of mistress' and strianed relationships, I believe Gatsby has some sort of history with Daisy Buchanan. If not history, then he lusts or longs for her. Why else would he be nervous around Tom Buchanan? In my opinion, this situation is foreshawdowing an event to come later in the novel between Daisy and Gatsby.