I have made an Earl Grey Tea extraction, it was not the best thing ever, tasted quite earthy rather than the floral type notes I was after.
I will assume that I left the teabags in the PG (in a kind of bain marie) for too long, so more tannins (or whatever) were released, giving a more bitter taste to it.
Next time I would just use more Teabags for less time.
I am not sure how good it will be using VG, but I suppose the heat will thin it enough to get decent steeping.
Good luck, I look forward to hearing of your results.