Visual puzzle

I am puzzling over an experience I had two nights ago: I enjoyed the warm evening by opening a bottle of wine in the garden. Some time later I was called inside for an hour or two, after which I suddenly remembered there was still half a bottle waiting to be drunk sitting outside. By then it was very dark, as cloud must have moved in and I could barely make out what was ahead. When very close I managed to make out the dark rounded shape of the table but at first I couldn’t see the bottle, which would have been within grasping distance. Whilst staring where I expected to find it, it suddenly appeared enough for me to make out an impression of its shape and to vaguely discern the label and top, but it kept disappearing for seconds at a time, then briefly reappearing over several cycles. I couldn’t get a continuous fix on it and it didn’t fade in or out but abruptly appeared or disappeared. I wondered if it was caused by blinking but found it not to be so. Then I wondered if it was caused by variable illumination falling over the table, but couldn’t find any occurrence of this. Anyone relate to this?