FCC and radio obscenity

Yesterday I was listening to the radio and the song “For You” by Staind came on. Now, there are at least 2 uses of the “F” word in this song - on the radio I have always heard them bleeped out. But yesterday, at about 4:30 in the afternoon, the station did not censor them. This is not the first time I’ve heard the “F” word on the radio (on various stations), but other times have generally been at night (I don’t know if this makes a difference). I personally see no problem with it, but I did think that there was some sort of an FCC rule against it. These are not tiny stations in small towns, either.

So if there is an FCC rule, is it just not enforced, or are the local stations just trying to push the limit?

(Later last evening, the song “Rollin’” by Limp Bizkit came on - they bleeped the profanity in that song, which is much more than twice.)

We had a very similar question recently revolving around the same word (but a different song) played on the radio. I will close this thread and direct further comment to the previous thread: http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=105007