Looks like little hops buds.
But seriously, it looks like the bud tip could have been fimmed either mechanically or chemically. Did you top the colas? Do you start using any additives from, say, 3 or 4 weeks into flower?
Is this the only strain that does this, or do other strains do the same, but to a lesser extent?
Weird but cool, lol. As long as after smoking it, it doesn't grow you another nipple or something...