That's too weird! I had them and I didn't use heat that much either.
I think mine was caused by severe dryness and rough handling. I don't have any now and my current regimen is basically:
- low-poo (I only use heavily diluted poo)
- oil pre-poo (again my hair can't be stripped of oil. it hates that)
- low-manipulation (both wet and dry). I wash in 5 plaits, I only detangle under running water (and I don't detangle every wash), don't brush my hair at all... EVER, and I only comb with wide-tooth seamless combs.
ETA: Oh and keep it moisturized. I noticed a few nodes (that I prompt cut off) after my last takedown. I was only moisturizing my kinky twists once every couple days
I have to use moisturizers daily and Aveda DR has been a Godsend for helping keep my hair moist. I've also discovered my hair loves oat protein. It adds slip and locks in moisture better than any product I've used.