I've reacently bought a festool TS 60 K plunge saw and after a brief use I was amazed to see that the green splinter guard that is mounted on the front of the saw was cut.
Is this normal, or have I missed some sort of calibration of the blade?
Normal. That is what creates essentially a zero clearance insert situation on that side of the blade with your guide rail strip creating the other side. I used to mark mine with blade type and setting depth on the older style of guards.