If you accept that 61 minutes for a woman would be suspicious, then you have to ask yourself where you personally draw the line. You're OK with 65 minutes, but what about 64, 63, 62?
Look at cycling. Cycling is convenient because we KNOW that most of the riders of the recent past were doping. We know that Marco Pantani was powered by EPO when he set the Alpe d'Huez ascent record of 37 minutes. So if somebody comes out and beats that time, their performance alone constitutes evidence of doping.