issue with my distributor points on my 64 Dart

I have a month old distributor that I put on my car. Drove it all day beautifully yesterday, today it would not start. I found out that the ignition point gap had changed spacing for some reason. I can wiggle the shaft that runs into my motor on the distributor back-and-forth, changing the gap size of the points. Is this normal? I know it’s supposed to be .017 and I set it to that, but it seems to run beautifully for a few minutes then seems to change again. Help!!