Probably a bit of both. Butt soreness is a plague of touring cyclist, and in my case, seemingly incurable. I stand for temporary relief, pedal awhile, stand again. Just tough it out. (You are wearing padded cycling shorts?)

Next bike shop you come across, you could switch saddles. Go for firmer with a narrow horn. Make sure it's adjusted so that your sit bones are centered on the widest part and the tilt is comfortable.

Many swear by the Brooks B-17 or one of it's cousins. Expensive, and takes a thousand or so miles to break in to it's maximum comfort level.

Be aware of the difference in generalized butt soreness, and a saddle sore. The latter is an infected area, often caused by chafing or an ingrown hair, that is usually a trip stopper.