Scab 4 weeks after stitches removed.

I had a mole excision mid November with five stitches (two deep dissolving). Stitches were removed ten days later and since end of November I have developed a scab that's still there (lower back) and I am not sure if it's normal. I thought that after removing stitches there should only be a red or pink ish healing skin that I can treat right away with vaseline to minimise scarring but as the scab appeared I understand I can't use it until the scab is gone. Is it something to worry about?