What does this mean ? Road rage or something else

So I was driving home on a dual carriageway this evening, I was driving fast as not a lot of cars on the road. Probably a consistent 80mph. When I had an Audi come up behind be and start to drive quite close. I was in the fast lane and passing cars so I wasn’t going to go back to the slow lane until I had a clear stretch of road. We was weaving across lanes clearly impatient or something. He wasn’t good at looking ahead though and due to slower cars got stuff behind a couple . Couple of minutes later when he had cleared them, he powered up to me again at which point it was clear and I moved over . Immediately after passing me instead of burning off into the night , once passed he slowed and touched his brakes lights on and off about 5/6 times (with no traffic in front ). Then went on his way.

What does this mean ??

I don’t think it was about getting past earlier as he didn’t flash his headlights or anything , and normally once passed you don’t hang around. Is this a known code for something ?

Interested to hear people’s thoughts on this.