Today I was watching the episode when Danny goes on his first date after Pam's Death on Nick at Nite. I noticed that on the top left corner of the screen it said "TV-PG" Was this a mistake or does this episode have that rating?

Thats the second episode! Maybe they, again, pushed the wrong button.

...this has already been discussed:

http://www.sitcomsonline.com/boards/showthread.php?s=&threadid=101951

LOL and sometimes they rate The Cosby Show with a TV-Y rating