Intermittent ghosting

Odd experience driving to work this morning. Every few seconds (say at 8 – 10 sec intervals) the rear lights of cars in front would suddenly multiply to form something resembling a string of continuous illuminated red ‘beads’ with no gaps bridging the gap between the actual lights, maybe 10 ‘beads’ long. This would last for a split second before reverting to normal. After about 6 - 8 minutes this stopped. Had a couple of other odd instances of double vision recently which I have previously queried on here, but I guess this was more likely to be ‘ghosting’ as it only involved lights. Puzzled at the intermittency in constantly reverting immediately back to normal as I have had vertical ghosting but this tends to persist for very much longer rather than flash and go. Subsequently, I’m wondering if it was related to my blinking, perhaps moving my contact lens, but then why did it stop after some minutes? Any ideas? Not diagnosed