Quote Originally Posted by cperiod View Post
Your offset is 15? The default value to lift before extending the probe (edit: Z_RAISE_BEFORE_PROBING) is 10. After the G28 it knows where Z0 is, so it's probably going to be as low as possible before deploying the probe. Try changing that to 18 or so. But I'd definitely look at a shorter probe; the z axis is slow, and that extra offset sucks a lot of time.
You might just be a genius. Not near my printer at the moment to try, but this sounds like a winner. I'll report back for posterity.

Edit: Looking at the firmware right now, Z_RAISE_BEFORE_PROBING is currently set to 5.