Yeah it's possible he wanted you to know, but it's also equally possible he didn't realize how conspicuous he was being. Just as it's equally possible that he didn't care how conspicuous it was.
As for a guy staring at a girl with B-cups. I've known a few girls with Bs that actually looked quite nice. Really. Furthermore, there are quite a few guys that just like nice boobs that are nice boobs, not discriminating because they're smaller. (I am one of those kinds of guys.) Just because they're small, doesn't mean they aren't nice to look at. Doesn't mean they don't jiggle or shake. Doesn't mean they're not pretty.
Also, while it does seem that they are in the minority, there are actually some guys who prefer smaller to medium sized breasts. Understandable, since it does make some things easier, and it does usually mean a smaller possibility of sagging, and increased possibility of perkiness. Small breasts can be fun.
So don't rule it out, or mark yourself down. He probably was checking you out.
lol My girlfriend just looked over my shoulder, reading your question, laughing and saying... "He's a guy. Smaller breasts are still breasts, and guys like breasts. Period. Get over it." and then she left the room.
Maybe he wasn't checking you out... or meaning to, anyway. Maybe he was.
There have been times where I thought a specific girl was giving me a disgusted look, and I find out later that it was because another dude was creeping her out and she was giving me a look about the other guy.
One time, a girl friend came in to hug a buddy of mine, and I wasn't paying attention; she had leaned over; after a few seconds of realizing that suddenly I had a view (though honestly I wasn't looking); I avert my gaze, and I look her in the face; She gives me a creeped out look. I was thinking that she thought she caught me looking, when was just kind of daydreaming and her boobs got in the way ( ;) )
Later, I find out she was giving me a creeped out look because a friend came up and hugged her that she wasn't close with at all, and she was looking at me like... "uh, what do I do?" It wasn't that she thought she had caught me staring; it was for something else.
or... maybe he was looking, didn't think you'd notice... or he wanted you to catch him. Who knows?