Easily scratched off skin bump

I accidentally scratched off a small skin bump (about 2x2 mm).  It half way planted beneath the skin and left a small blood spot.  I did not get a chance to see its color or shape.  It concerned me now what kind of mass is so easily scratched off.  Do I need to see a doctor, since I had skin cancer 5 years ago?  If yes how soon?  Could I wait for a while since it was a small bump?