Raspbmc GPIO IR receiver disable when not being watched

I have just set up my spare Raspberry Pi B+ (since purchasing the new model 2 :-)) as a media player for my children. It is stuck to the back of their Samsung TV, connected using HDMI and works a treat. However, I have added an IR receiver (GPIO) and programmed the Samsung remote control buttons and I am having a problem. As the Pi is always left on (powered by mains and not the TV’s USB port) the remote control is controlling the Pi as well as the TV when they are watching normal TV, browsing the TV guide etc. I do not wish to buy another controller for them to lose or break, so wondered if there is any way to disable the Pi’s GPIO IR receiver when the Pi is not being watched. I was thinking that the TV might send a signal through the HDMI when the source is set to the Pi, so I could listen for this and enable/disable the IR receiver depending on whether the Pi’s HDMI source is selected. Any help (or other ideas) would be much appreciated.
Kind regards,