It's a phenomenon that's happened to me. I attributed it to stress because only a few side branches started flowering. I cut off the flowering branches and went on without them. I've quit keeping mother plants as I tend to go from strain to strain, but stress will cause a mother to flower.
about 4-5 mo old,,, was due to go into a bigger container,, 2 feet tall, and in a 8 in planter,, im gunna get a 1 gal,,, (lol mamas a beast,, flowers turn a blue n white shade, smells like,, ummm, lemondrops and sugar,)