I just dinged 15 and I thought it was a bug that no talent appeared since it made a flash beneath the portrait and nothing appeared. Then I checked my character sheet and one white talent used on an item is changed to a squared one. Maybe this could be made more obvious?
What's even more funny is that if you would take all of your items - you suddenly have one more talent. I find this to be really hard to tell wherever I've gained a bronze talent or the white talent in fact has became a bronze one - it's really hard to distinguish. Yet another finding: as a safe work-around I would suggest taking all of your gear on every single character on level 15-20 as you might find out that you suddenly have one more talent to spend than you thought - it's truly mysterious to me and rather dizzes my head - would be able to make safe assumptions if I knew for sure how many talents I am supposed to have on certain level - but unfortunately I do not know that yet.