I got it, my first runner's high! I know about the swimmer's high; experienced it back in the day when I went swimming regularly. Usually when I had done 1km, it felt like I could go on for hours. I figured it would take some more time for it to happen with running, but fortunately it came pretty soon.
It was one week ago. The weekend had been pretty crazy (with the wedding and all) and Monday evening I set out to go for a leisurely run. The temperature was perfect, it had already started to cool down a bit. The sun had started to descend but it was not dark yet. After the weekend-long orgy, I had eaten a light dinner. As a result of all these factors, the run was just perfect. I wasn't breathless at any point, didn't get those fracking side-stings and 30 minutes in, I got my awesome runner's high. "King of the world, baby!!!" The thought of extending my run crossed my mind, but as a beginner I decided against it. In hindsight definitely the right decision.
It's every bit as amazing as I hoped it would be. I can't wait for the next one.