Haha yeeep, thats what started happening to mine I think about 4-5 months after I bought it. Started doing the double/triple slaps on the shutter press every once in a while and I think it was extra twitchy when I had oldies on like my Juptier-9, Kiron 28/2. I remember it was going off quite a bit with my T-Mount Rokinon 500/6.3. MightyMike remembers haha. My camera was sittin' on the grass no standby and the camera would be just slapping away, randomly.
I've had continuous slaps before. Really annoying and people look at you funny. Often popping the batteries stops it for a while.
...but enough was enough and its now at Pentax for treatment. Its gonna be in for a surprise when it gets back and there's a K20D in its spot in my bag
Yea, I'd take it in for repair. I've had the Samsung GX-1L, Pentax K100D before it and never had such happen regardless of lens.