Out of the box, after updating today to 7.1.0, converted the Weather page from table to TelerikGrid component and the date was being displayed with coma as separator. My html tag's lang was set to en-US, and the SatelliteResourceLanguage property was set to en-US, my OS's regional setting is US and yet the display was European culture.
var cult = CultureInfo.GetCultureInfo( "en-US" );
CultureInfo.DefaultThreadCurrentCulture = cult;
CultureInfo.DefaultThreadCurrentUICulture = cult;
Adding the above code, resolved the issue. But my expectation is to default to the system's culture even when the application is supporting globalization/localization.