First of all, there is a pretty wide range of attenuation for a given yeast strain depending on a whole lot of factors - fermentability of the wort, oxygenation, fermentation temp, etc. If a strain is listed with an attenuation of 75%, then I'd say anything 3-5% above or below that is within a normal range.
Secondly, WLP 565 can easily hit 95% attenuation if you handle it properly. A lot of times there can be a lag of a couple of weeks where it stalls out before it eventually finishes up. Are you 100% sure that it has finished out? I'd be scared as hell to bottle any Saison strain at 1.012 unless it was rock solid at that number for at least 2-3 weeks. Please be very cautious of bottle bombs. Check your bottles frequently, and if you start seeing any signs of overcarbonation, chill them and drink them ASAP.