Glycerine tincture contamination?

Hey guys so a while back i finished my first glycerine tincture and a few hours after i put it in the fridge i noticed there seemed to be a white foamy substance sitting on the top of the tincture anyways over the past few days there seems to be more and more of it, so its making me wonder if i have a contamination or something, i have tried searching google but i haven't found any information on it, what do you guys think? I can post a pic if needed.

bump anyone?

It could be some type of by product from the glycerine manfacture process - Glycerine is usualy a byproduct of soap/biodiesel manfacture

Also glycerine is very Hygroscopic (sucks water out of the air) , The water could be combineing with impureitys from the extract and causeing issues

I have made gev. glycerine and have never seen the impurity you talk about

i got foam once too . it was fine for my dome plate . try not intoducing so much air

I did put the lid on the mason jar while it was hot could that have caused contamination? I was wondering if maybe the foam is just leaf matter that escaped threw the cheese cloth and it is getting pushed to the top because the vg is heavier than the matter.
I guess i have no real way of knowing, i've searched all over the web and i cant find anyone showing examples of contaminated tinctures nor have i been able to find anyone on google that has a contaminated tincture, its fucking weird it seems as though there has a never been a case of a contaminated tincture documented in the history of google.