Question

n sib   hi i live in western pa

i have a N Sib which has developed small dots on the under leaf
almost like some thing is eating them as a new leaf forms then the dots become darker as the leaf ages.
i use a soil that is just LFS and perlite

Answer
It definitely looks like you have a pest problem.  I'm not exactly sure which pest, but the bumps are a clear indication of some sort of pest is biting into the leaf.  You can use a contact or systemic insecticide.  If you use a contact insecticide, you will need to repeat the application in 5-10 days, until the infestation is eradicated.  The insecticide will not reverse the leaf damage.  That damage is permanent. However, it will prevent further damage to your plant.  For information about safe insecticides to use and the proper application of them, watch our video podcast on the topic.  
http://youtu.be/lbRCdJ8ZNF0

Good growing!
Jacob Farin