Im not sure if its helpful but on my first ride (2 weeks ago) I felt the same, very stretched out. I am now feeling much more comfortable and my body seems to have naturally found a position which is comfortable to me and don't feel stretched any more. My rear end is also tough as old boots now and don't feel uncomfortable, not even in padded shorts.
My advice is give it a couple more rides to see if your flexibility improves etc.
My advice is give it a couple more rides to see if your flexibility improves etc.