Replying to Full Tilts ( Hot Dogger) Help

I have the new full tilts and I went skiing with them for the first time yesterday.  When I was skiing my lower leg muscles around the calves area were hurting.  It felt like the boot was putting too much pressure on them.  I then skiied with the top buckle off and that felt fine.  My question is what could the problem be?  Is it the process of breaking a boot in?  Do I need to mold it?  The size is not a problem, I'm not worried about that.