Heel lift when walking in bike shoes

As the title states, I have a pair of Specialized Recons and they fit great when riding, but get considerable heel lift when walking around. I did get the correct size and notice that I only experience heel lift if I wear thin cycling socks. If I am wearing regular athletic socks I get no heel lift. I don't know if its the slippery material of the sock or the fact that the sock is thin that is causing the heel lift.

Is heel lift while walking normal? I am sensing it is due to the stiff sole, but it drives me crazy.
I would wear regular athletic socks while riding, but they make my feet to crammed in the shoes.

Any advice appreciated.