I no longer feel excited when I watch Dexter.

This happens to me almost every season, but it's like I don't feel the same emotion as in seasons 1, 2, 3, or 4. For example, the scene with Angel and Harrison seemed interesting to me, but it didn't I was moved, nor did practically anything in Original Sin, except for the scene with the drowning boy. Does this happen to anyone else? Is it normal?