Check the hgh power sponsor thread there is discussion about it. I got them all of a sudden on Kefei's even though I never had them for months prior. I switched to IM and it still occurred but eventually went away and I slowly went back to sub q. It's kinda worrying though, I always wonder what happened in my body exactly that adjusted to it and also why can't anyone pinpoint exactly what causes it. I did a lot of readinf and researching and there are lots of theories but never found any definite evidence. One specifically regarding your body becoming immune or desensitizing to GH is particularly worrying.