wrong size battery posts

Bought a new battery while I was a t the dealership the other day. When i was driving home tonight is seemed that my headlights were flickering. They never really dimmed all the way just seemed to get brighter and dimmer with bumps. Well I got home and started to troubleshoot. All the headlight wiring was tight but I could pull the Positive lead off of the battery by hand. I tightened it all the way but it was pretty much already there. Any one else get a battery/ battery post from honda that was the wrong size?

thanks in advance for any input

Take it back to the place where you bought the battery and make them make it right. They have lead caps they can put over the post that will allow tightening cable bolt. How does the neg. cable fit?