Some of the over-valuation is there anyways because the CHF has always been a safe haven.
The Swiss currency sees a lot of demand because of a current account surplus and rock solid finances. That is why they have had to set a negative interest rate. But yes I see your point and expect lot of these big moves are shorts being squeezed out. The SNB has already said it prefers eur/chf at around 1.10 so we will have to see if they go along with QE.