I was sunburned last april. there was no blister, just inflammation and hyperpigmentation. now the skin on my arm is rough and dry than usual. moles appear normal. is this physiologic response and will it eventually returned to normal?

Depending on how much inflammation and hyperpigmentation was present would help determine how long it would take for the skin to be normal. Rough and dry skin is best treated by applying a lotion frequently-lotions with vitamin E are helpful in these circumstances. Applying sunscreen when sun exposure will happen is crucial as well to prevent further skin injury. Best of luck to you!