Hi Bone011,
When I went to my Gyno surgeon he told me that my boobs would be dropping further down as I age. I can see that happened because I am 31 now and almost the same weight plus 5 to 10 lbs heavier. I can see my nipple area has began to have that drooping look.
I don't know if this is common for everyone else, however my surgeon stated it happens with age. So unless your some kind of gym rat this could eventually happen.
Luckily for me it won't anymore since I had my gyno surgery last month. Going on 3 weeks!