Common Loons typically don’t establish a breeding territory until they are a few years old. Young birds stay farther south during the breeding season, typically not returning north until their 3rd year.
This is probably just a case of mild vagrancy. Maryland is just east of their breeding range in Appalachia.
Ring-billed Gulls take 3 years to reach adulthood. Immature/juvenile birds regularly winter as far south as Florida in the eastern U.S.