Congrats on a nice harvest, you buds look great! If the trichomes are good then your potency should be, too!
As far as the new pistils, the first thing that comes to mind is perhaps this strain needed shorter days (longer nights). Some strains from the equator can take months unless you give them longer dark periods like 13-14 hours/day. Do you have pictures of the plant at various parts of the flowering stage in the setup? I could also be an aspect of the genetics/strain. My other thought is perhaps your plants got some amount of light at night, even a tiny amount like from an indicator light? That could possibly stop the buds from maturing.
Overall it looks like you harvested some fire!