earphone buttons stopped working on multiple devices

Hi,

So I recently purchased an iPhone 5 and the store gave me a pair of additional earphones with the deal. All new products. Earphones that came with the phone works fine across multiple devices and so did the extra pair, until earlier today.

When I plugged in the extra pair into my macbook, the volume/pause button suddenly stopped responding. Sound works perfectly fine but the buttons don't. After this happened I tried plugging the earphones back into the iphone and the issue remains. Even tried them with my old 3GS, same problem there. Original earphones still work flawlessly.

Why can this be? The earphones are new and the buttons worked fine until I plugged them into the macbook. Is there anyway I can "reset" these earphones?