volume buttons both increase the volume

After replacing the headphone jack flex cable due to a bad headphone jack, the side volume buttons both increase the volume. All other buttons connected to this flex cable are working fine - mute, power.

I have restored the iphone via itunes to the latest 4.2.1 with no change. Interestingly, when I first replaced the flex cable both volume buttons decreased the volume but after taking it apart a few times, they now increase the volume. Could this be a bad flex cable or a logic board issue?