I have started to notice that after I strop my razor there is black on the spine of my razor and I it may be on the blade also. I have to wipe it down with a clean cloth or tissue to get it off.

I don't think I am using a lot of pressure, if any at all. I hook the strop onto a towel ring and hold it tight toward me. I (at least try to) put only enough pressure to keep the blade against the Black Leather Strop, holding it with the top of my thumb and index finger. it does sag just slightly when stropping, but I still hold it relatively tight to keep it straight.

The strop does have some nicks and cuts in it that I tried to smooth out using my SO's 5 way rectangular nail file, not sure if doing that is what is causing it. I have also noticed that when stropping I tend to hold the razer a little sideways rather than straight.

What do you think? Am I using too much pressure or did I mess up the strop by using the buffing side of a nail filer? Or is this somewhat normal (don't think it is though)?