Am I weird? Sometimes a tv show theme song can actually make me cry. It happens with movies all the time. When I went to see first of the new Star Wars trilogy, The Phantom Menace, I cried while the opening played. Of course, by the end of the movie I was pretty pissed at George Lucas, but that's another story.
I guess I'm overly sentimental about my childhood, but I'm not sure why. I certainly didn't have that Brady Bunch upbringing. Maybe I'm sentimental about what I wish my childhood was or maybe lines like, "you're gonna make it after all" are just so hopeful they can't help but bring me to tears.
I was too young to watch a lot of these when they were new, like Mary Tyler Moore and The Brady Bunch, but I watched a LOT of tv as a kid and the late 70s and early 80s were rerun heaven.