Was the 'I' gone (for a moment)?

Can someone explain to me this phenomenon that has happened to me? I am not a serious Buddhist practitioner. I used to do mindfulness practice daily (20–30 min on 90% of days), just observing normal breaths or maybe counting the breath. Last night I didn't get proper sleep so I just started observing my thoughts. Images started appearing and disappearing and also voices (as if I were talking or someone else was). Whatever we call reasoning is again a sequence of images and voices. The **'I'** existed in the images and in the voices (as in *I did this, I have this work, I had headache...*, something like that) and, at the same time, the **'I'** did not exist and everything was just a sequence of thoughts (voice or image). As a consequence, any egoistical thing like a superiority complex or that kind of thing made no sense – but this whole experience lasted roughly for 3–5 mins. I am slightly hesitant to use word **I** this morning but yet somewhat comfortable. Can someone explain this phenomenon to me?