Purple leaves are a feature of some varieties of flowering indicas. It is a genetic characteristic and is often provoked by a sudden cold weather spell. Nothing to worry about...I think it makes the plant very pretty !
Thanks for the info. on the herb scene in Lausanne. It sounds pretty much like Fribourg in terms of price and quality. Yeah I know about Bienne and the head/coffeeshops there...I normally pick up some good hash in Basel if I feel like a change from my own weed. There's a couple of guys there who only make hash....