Now, in the light of the last episode...
Remember what Hurley told Sayid in "The Long con" (2x13) while listening to the Moonlight Serenade (a song reminiscent of the 30s, 40s).. he argued that the radio could be picking up signals from...anytime. No doubt he was joking but what if it could be a TPTB reference to time travels issues?

Here's a passage from the transcript:

RADIO [with spotty reception]: That was the old classic Just A-Sittin' and A-Rockin' by Duke Ellington and his Orchestra, featuring Cootie Williams on the trumpet. Up next on WXR, the Glenn Miller Orchestra with Moonlight Serenade.
[The song begins to play with good reception.]

HURLEY: Whoa, you hear how clear that is? It's got to be close, right?

SAYID: Radio waves at this frequency bounce off the ionosphere. They can travel thousands of miles. It could be coming from anywhere.

HURLEY: Or, anytime. Just kidding, dude.

Or maybe they were picking up the radio from the Hydra island that the others play-like when they "buried" Colleen they were playin old-time music.