Seems like a clear downforce-issue with the front spoiler or perhaps front suspension?
What was the tarmac/autobahn like? Totally smooth or a bit bumpy?
If the suspension is too hard or the bound/rebound on the dampers isn't reaction fast enough to bumps in the road, the car will feel light, jumpy and have reduced road contact at high speeds.
Both uncomfortable and potentially pretty dangerous.
I dunno the F430 very well, but if there's a soft and hard suspension option, maybe you should try the softer one for your next hi-speed test?

Damn, that's a beautiful pic you've taken. It looks stunning from behind.