I also use high percentage of PG most of the time (70% or 80%) and that might make a difference as well.
That could be it... I try to stick to 60% or 50%... I ignorantly ordered some 80% 555 and it gave my otherwise rock solid evod a bad case of dysentery. I ended up cutting it with a 100% VG tobacco I have (ended up making a halfway decent juice actually). I have a Vivi around here somewhere with some 80 in it, I'll throw it on my Vamo and goose it a bit and see what happens.