(Spoiler warning: Don't read this if you haven't seen Sunday's "Mad Men," entitled "Favors")

Bob Benson might be gay — or just a shrewd manipulator of 1960s homophobia.

The crucial moment in Sunday's "Mad Men" was Sally Draper's terrible discovery of her father having an affair with his neighbor — but the episode also slipped in a tantalizing new clue about Bob's mysterious motives.

Also read: 'Mad Men': Matthew Weiner on Whether Bob Benson is a Spy

Last week, "Mad Men" creator Matthew Weiner declined to comment to TheWrap on the widespread theory that Benson (James Wolk) is a government agent, sent to spy on serial liar Don Draper. On Sunday, we were offered another possibility: Bob is constantly on the wrong floor, offering his services to everyone in sight, because of a sexual interest in at least one of the men of Sterling Cooper & Partners.

But I think that suggestion is classic "Mad Men" misdirection. In fact, I'd argue, Bob has masterfully identified and exploited Pete Campbell's greatest insecurity.

We received our signal that Bob may be gay or bisexual when he appeared to proposition Pete (Vincent Karthesier) in a closed-door meeting about the nurse Bob referred to Pete to care for his mother. When Bob mentioned the nurse's likely homosexuality, Pete called him a "degenerate." Bob then began a short monologue about whether you — he used the second person — might fall in love with someone who dutifully attended to your every whim. As he spoke, he touched his knee to Pete's.

Shouldn't he have known from the "degenerate" comment that Pete wasn't gay? Or did he see it as Pete overcompensating, as a cover? I think it's closer to the latter. But I don't think Bob really thinks Pete is gay.

I'm guessing that Bob has guessed — correctly — that Pete has doubts about his own masculinity. That's why he asserts it constantly with his too-big sideburns, his frequent affairs, his phallic hunting rifle. In Pete's homophobia, he of course interprets homosexuality as unmanly.

So Pete isn't worried about whether to have sex with Bob — he's not interested. But he is deeply in his own head about what signal he gave off to make Bob think he might be gay. He goes home at night to his empty apartment, where he also finds his cereal box empty — because he no longer has Trudy to cook him manly dinners ("ribeye in the pan, with butter"). He hurls the box at the cabinets. No gayness here.

Bob, meanwhile, is in a good position. He's psyched out a potential rival, and if Pete later accuses him of propositioning him, then Joan, for one, will attest that Bob sure doesn't seem gay to her, based on their previous history.

But Pete won't say anything, because he fears that that, too, would raise questions about his manliness.

Weiner told TheWrap last week that Bob is "definitely a liar," adding, "I'm not going to comment on whether or not he's a government spy, but James is a great actor, and he is definitely mysterious. And that's deliberate. He has very good manners, and that seems to be working for him."

On Sunday's episode, Bob stopped being polite. But that doesn't mean he started being real.