DDH,
I was plenty sore after getting on a bike for the first time in 37 years last month. My thighs, my shoulders and arms, and especially my behind where I sit. But it slowly faded away after a few more rides- about 2 weeks worth.
Don't forget you are using muscles and tendons that haven't been asked to do much of anything in a long time. You are making demands from muscles that you don't even have yet!
Be patient. The body will respond.