Yep, it can be.
With my first pregnancy, the breast soreness kicked in before the morning sickness, but it never got too bad.
My second pregnancy, just the air touching my bare breasts hurt. It was awful, and it started before my period was due.

Agree - my breasts were really sore then I tested 4 days before my period and it was positive. A couple of days later my nipples were sooooo sore to touch and so were my boobs.

Sounds like preggy symptoms.

My nipples are tender to da touch but my first first sign was the metalc taste in my mouth!! And I had it for 3 days!! I didnt even know it was a symptom!

Oh gosh it was sooooo nasty. At first I tought it was my gum bleeding lol

My gums have been bleeding for the last week! Yuck!!!

Last week I tasted blood a couple of times and this week every time I brush they bleed and that's never happened to me either! I take it it's just another thing that comes with pregnancy!

Oh my god.

I never had that in my two pregnancies, but would you believe I have it right now??
I've been feeling like I might be pregnant, but I keep getting neg. Hpt's- got one this morning as a mattter of fact. I've totally skiped my period- nearly 3 weeks ago now, so i'm not testing too early.

Wonder what the story is?? Oh well, I guess time will tell.
How bizarre.

Yes it is a sign but it all depends on when you implanted. The average is 9.1 days but it can happen anywhere between 6-12 dpo.