Very strange occurence with my bike. Engine lost power suddenly and regained it after a few kms

I drove to my college today at 9 AM. Since it was a cold morning, i used choke to start the engine. After letting it idle on choke for around 2 minutes, i started off. Drove at higher than normal speeds (around 80kph) as i was getting late. Nothing new, have done this quite a few times. After riding for around 3 kilometers, all of a sudden I felt like the throttle was not responding to my input. I had twisted the throttle around 50% of the way up, but the engine was at 4000 rpm only! The speed was 50 kph, which is normal in the 5th gear

Not being able to understand what was happening, i twisted the throttle all the way up. Usually, the needles would climb and the bike would touch 70-80 kph in around 10 seconds. Not today. It took around 30 seconds just for the RPM to go from 4K to 5K! The speed was not going above 60 kph, although I was giving it full throttle!

I was scared as yesterday I had tuned my carb and made the mixture leaner. I wondered if i'd messed up the tuning and torn my bore or something. I thought that i'd investigate it after coming back from college, as i was already late. After riding for around 4-5 kilometers, i slowed down at a traffic jam. Didn't stop completely, but slowed down to around 15-20 kph. When the traffic cleared and i accelerated, all of a sudden, the bike was back to normal!! Just like that! I didnt even shut off the engine, just slowed down, and when i speed up again, its back to normal.

Any clue what just happened?