Regardless of whether the valves actually contacted the piston or not, I can tell you for a fact that what I see is NOT normal on a Ford (I've worked on dozens of those engines). Something inside that cylinder is too close for comfort, and needs to be looked into, in my professional opinion. If a wrist pin or rod bearing is on the way out, now would be the time to catch it.
One thing I would do is measure the valve recession on all the valves. If the valves are all pretty much the same and within spec for recession, I would suspect a bearing going out.
Another very distinct possibility is that what we see is contact damage prior to the last (and very recent) engine rebuild. This assumes of course that the pistons were re-used, which I have done often myself on Fords. Those pistons are very tough.
One more thought: If you think that's normal, why does it show on only one piston?