Kick start going down while riding

Hi all

While riding my 1968 Atlas on sunday i had just refueled set off just changed into 3rd & felt something hit my right foot i looked down to see the kick start lever at its full stroke down then the rear wheel locked up i instantly pulled in clutch but the wheel was still not turning

Later after getting bike home after it cooled down every thing ok kick start working as it should I have took off outer cover & inner looked at the inner bush on kick start shaft it apears ok as far as i can see its the only thing that could cause the problem

I must add this is the furthest i have ridden the bike about 150 miles in total on sunday the most ive done before is 40 miles eat a ice cream then ride home

Your thoughts are most welcome thanks Nick