Firstly we would like to reassure customers that it is not a fingerprint. The process of filling and putting the lids on the tins wouldn't allow a finger into the balm.
The lid is screwed on by a machine while the balm is still in a hot liquid state.
However due to some movement a swirl can be created that might reach and touch the lid. Or the insert inside the lid can drop a bit and touch and become loosely fixed to the balm. Once you open the tin the little swirl is pulled around the pot and can create the effect of a finger mark.
If you do have this mark on your balm you will normally be able to find some light balm residue on the lid insert where it was in contact.
There is a picture below to show a fresh opened tin of balm showing the mark and the residue on the lid.