The wrap of all three batteries I just bought 3 days ago all have dents on them around the perimeter on the positive side of the battery and I'm pretty sure it's because I have to use my fingernails when removing the batteries from my mod as I can't find another way to do it I'm going to try to enclose a picture and anyone tell me if this damaged is anything to worry about.
It could be because of your fingernail, and like what Tonee said, there's an insulator ring on the top side of the battery. Most of the battery casing is made of metal. The tab at the top of the battery is the positive. There is a thin space between the tab and the rest of the battery case, but the outside battery usually wraps a little around the top corner. This is what it looks like unwrapped:
Now the problem is, the very top raised area is the positive, and the rest of the side body is the negative. Battery companies put a thin plastic "washer" to only expose the positive on the top of the battery. They then put some shrink tubing to insulate the rest of the battery. The result would be a reinforced top, with some shrink wrap around the rest of the body, with an exposed area at the bottom being the negative. This is so it doesn't accidentally short the battery when putting them in or taking them out.
If it is denting the top, chances are, you're denting the thin plastic that seperates the positive from the negative. This is either from your mod or fingernails. I would check the mod first to make sure it's not the culprit. Sometimes there is a small piece of plastic that migh be causing it.
If your fingernail is doing it, try to find another way to remove the battery without damaging it. Over time, if that plastic breaks, it could cause a short. Most companies put in a thin ribbon in the mod to allow you to pull the ribbon to eject the battery.
Make sure you put the battery on top of that ribbon allowing you to pull the ribbon taking the battery out. If it doesn't have one, I would make one like Firestorm and zoiDman suggested. if it becomes too damaged, you can re-wrap the batteries by buying some sleeves. Most local Brick and Mortar shops sell some, and are quite easy to do.