I can feel my heel lifting in the boot, is that bad?

Yes. No one likes heel lift. Heel lift is a very common complaint of Ski Boots and there are many reasons for this to occur.

The boot could be too big in the length or it could be too big in regards to the fit. The boot could be too soft and allowing you to over flex and letting the foot get to a position where it’s trying to walk!

If there is no custom footbed stabilizing your feet, that could be the cause of the movement or you have skied over 200 days in your boots and the liner is starting to pack out and simply not doing its job to support you in the shell anymore. Sometimes a piece of foam added to the liner in the shell can help with this as a short term fix or with difference in fitting with our feet that are different left to right.