When Aria is in Ezra's apartment alone and is looking through his notebook of research on her (& her friends / Ali's disappearance) one of the notes says Aria spent three years in Iceland with her family instead of just 1 year and it also states that "a few years went by" and the girls grew apart after Ali disappeared but it was again only 1 year since the anniversary of that night when the pilot started and the girls started talking again.