chitty
not sure if your feeling any discomfort but looking at the angle on you seat, it seems to be on a forward angle. i used to ride with my seat a little bit forward and after long rides (50 + mlies ) i got major pain in my sit bones. i went and got fitted out at the local bike shop, and they adjusted my seat by 5 mill backwards and the difference was unbelievable. i was then doing regular 100+ rides with my bike club and not feeling the pain that i was having previously. it really is worth the effort to have your riding position sorted out at a good bike shop if your doing long rides,even if you dont feel any pain at the present...
happy riding