How do get DateTime of a TrackerHitResult?

I've implemented MouseDown on my plot, it has a LineSeries with Y as a int type and X as a DateTime. Its displayed nicely, but when I click it i get a double as date:

Plot plot = sender as Plot;

var series = plot.GetSeriesFromPoint(new ScreenPoint(e.GetPosition(plot).X, e.GetPosition(plot).Y), 10);
var result = series.GetNearestPoint(new ScreenPoint(e.GetPosition(plot).X, e.GetPosition(plot).Y), true);
var data = result.DataPoint;

data's X should be a DateTime value, its a double, but how can i convert it back to DateTime?