Good thought. I can see that logic in an American location reaching out to google.de. But what about a German location seeing almost all English results -- I wonder what that logic is.
Well assuming they had no way of pegging you from cookies/browser/google toolbar, I'd have to guess it was what you asked for that triggered it or how you asked.
Maybe its as simple as how they handle regular queries, they look at the click through and return rate and saw that everybody who did that particular query picked an English result page. Is that possible?
The interesting thing would be if you allowed google to localization/personalization, at which point they would have started giving you the German results only.