Yes they should be protected if you stack them. If you're careful and gentle when you stack them a paper towel is enough. If you're not so careful I'd recommend you use a kitchen towel.

I have a stainless steel frying rack that I got from TJMaxx. It allows me to store 6 frying pans vertically. Another benefit besides not scratching is they are easier to take out of the cabinet since they aren't stacked.

Yes, like Mustangs, my pans are also stored vertically. You can get the rack to put in a cabinet or drawer and line the pans up. They are so easy to store and grab, I'm wondering why we haven't been doing this for years! I got mine at Organized Living.

I use squares of bubble wrap....the kind with the small bubbles.
Linda C

Anther method: Use disks of cardboard cut from boxes (like the ones the pans came in). This has worked for us for some time now (being short of storage space!) Steve

I just use pieces of shelf liner. It works great.

For lack of enough room (who doesn't need more room...LOL), my pots and pans are housed in deep cookware
drawers, sometimes stacked inside each other out of necessity. I cut squares of cushioned shelf liner to put in between the frying pans. I only have one non-stick frying pan, but I use the squares to protect any cookware that sits inside another one. The shelf liner is cushioned, washable and re-usable.

We too have just one non-stick skillet. We are careful to store it on top of the stack.

I sometimes keep the protective wrapper the pan came in, if it is fitted. I also use flannel rounds. For my long griddle which I store in the bottom of a drawer under large stockpots, I cut out a piece of cardboard to fit into it to keep it from scratching.

I had left over pieces from the cupboard liner that I used (Cushy Cupboard). I cut circles for each pan. At the cost of pots and pans today, they need to be protected. I got my cupboard liner from www.cupboardliner.com. The service was great and fast.