Phone Call From Zero

On Friday night (28th August) my girlfriend and myself were in the front room watching some evening T.V. I'm not 100% sure of the exact time, but it was around 9:40pm. My girlfriend had the landline phone resting on the side of the chair she was sat in, and I was sat beside her in my own chair.

Well the adverts had just come on and the panel on the phone lite up and the phone display showed zero.  It wasn't an incoming call as the phone never rang, and when I checked with call back it quoted a time from much earlier in the day

Now I know this may sound really crazy, but even my girlfriend said that maybe it was the ghost, but I explained it as being a fault with the phone, but we both saw the phone do it, and both looked at each other.