I use Johnson Creek NON-PG and have ten 30ml bottles here --non of wich have any issues. And they are on my desk in the blazing sunlight of sunny Florida. 

So some batch's allegedy got messed up. (1) They are going to report on the problem once they get the lab results back, (2) they are refunding anyone that had a problem, (3) the problem affected a very very small percentage their product, (4) noone reported getting sick from the problem--Does anyone think China manufactures would be on it and make good if this happened to their e-liquid?? Do you think you could even get a hold of anyone in China to see what happened?? So I think we should give them a break here. I use their product all the time and have ten 30 ml bottles here with no problems so it appears to be an isolated incident. They are making good faith inquiry and they are responding. What else could we all ask for???????????
Another problem observed only with inhibited propylene glycol is the presence of particulate in the glycol, e.g., green in colour with Dowfrost HD, which is due to elements in the inhibitor/buffer package coming out of solution. This does not mean that the glycol has failed, but the particles may clog a strainer/filter if one is in the glycol-charged collector loop.
This causes high solar collector temperatures on hot, sunny days and this, over a period of time, causes a breakdown in the glycol. It may become black (carbon particles) and/or very acidic. The black particles can accumulate at a bend or crevice in the collector loop and cause blockage of flow
I just had a 30ml bottle of PG peach cobbler turn green on me today after owning it for nearly a month. It was the regular color, until I decided to use the dropper from the bottle to mix my own juice (as for some reason I can't find a dropper in ANY local stores). The JC turned green within an hour of my mixing. The contaminants were: Lorann apple flavor, usp grade glycerin, and possibly a bit of saliva because some part of me really wanted a drop of straight apple flavor on my tongue. I did rinse it lightly in regular tap water before re-inserting it in the JC bottle. Within an hour or less the contents of the bottle had turned a much greener hue. My guess is this has something to do with contamination, either from contact with carts, or some other source.
Hopefully we'll get some lab results soon *crosses fingers*