You know, I was gonna agree with you at first steven115, but the more I thought about it I realize it's definitely not true. How often do you just hear about a girl bragging about her hair, nails, clothes, boobs? It's rarely ever bragging per se, it's usually a "Hey that nail color looks really cute on you" "yeah I really like it, I was trying to go for something relaxing and soothing, not very loud" blah blah blah.
Granted women may seem to have more of that than we do, but it's only because men don't engage in those interactions at all. A woman getting ready for a party might hear "Wow sexy cleavage you've got going there", But no one, barring their significant other will likely tell a man he's packin a sexy bulge, or that his muscles are looking really toned and firm, or that his hair looks just bedhead-ey enough. And maybe that's a whole separate issue entirely.
As far as bragging in general, I dare say everyone would have a problem with anyone bragging about anything, so the issue wouldn't be that you're bragging about your dick but that you're bragging at all. When is bragging ever really tolerated?