I'm 30 and just noticed a soft lump in my breast, should I be concerned?

Breast lump. Unfortunately the only thing that can be done online is to recommend you see a doctor abd be examined. Given your age it's most likely benign, but we can't be sure. If it's round, soft, movable, symmetric, and if by your next cycle it disappears then i'm less worried. Same if you have no family history. Still, see a doctor to be sure.