My boyfriend's ex?

Is it a cause for concern if my boyfriend still checks up on his ex and his ex's family? The first year of our dating, they would all still text on occasion. Now, on our second year, he does not communicate with them anymore, but still searches them on Facebook a good number of times. He's loyal and loving and still acts like a typical long-term boyfriend would, but I can't shake the feeling that he's not over his past.