Relax and quit overthinking. It would be impolite if he remained silent. Of course, if you texted him that you were going to bed, the polite thing to do was to say goodnight. He could have been interested if you had been messaging him for a while, but I don't believe simply because he said goodnight signifies anything. It might be construed in any direction. He hasn't been at work for 12 hours straight, all day, with no prospect of responding to your SMS. Unless he's a deep sea fisherman in the Bermuda Triangle, there's no way he could have been detained at work all day with no way to reach you. He was also not called in at 10 p.m. on a Friday.