The DatePicker and the TimePicker should use the same margin / padding as the TextBox. Currently the spacing is slightly different. I think from an aesthetic point of view they should match. You will find a screenshot here:
This minor flaw does exist in the previous toolkit and the November 2011 edition. But I think with the November edition I see another issue. I had no time to check it but prior to November the FontSize of the Pickers was equal to the TextBox (as in the screenshot). However with the November edition it seems like the FontSize has been slightly increased as if a non standard style has been applied. Visually this increases the impression that the design of the DatePickers and TimePickers is not consistent with the other elements of the WP7 UI.