6m - WSPR very early Es?

As early as 0402z DB0ZDF (608km at -20dB S/N) was spotting my 1W ERP 6m signal by Es today. Apart from this single report, just the usual GDX stations (out to 184km) no doubt helped by aircraft reflections. I am assuming DB0ZDF was Es; it is possible at this range it could have been tropo or aircraft reflection too.