Welcome to HCM.
supporting the testis has a unique muscle called DARTOS that is sensitive to temp changes of the environment.
By this action, testes stay close to the body in cold
temperature and away from the body in warm climates.
It is unlikely to be anything abnormal, but a physical examination is advised if you are worried.
The groin on your description, if looks flat should make you happy as fat deposits make it appear worse.
Wishing you good health