Any time you have a mark that concerns you, it is worth having it checked out. Having said that, the photos do not show a mole with typical characteristics of melanoma. This mole or birthmark appears to be very flat against the rest of your skin, which is not usually the case with melanoma. You can find pictures all over the internet showing typical malignant melanomas - this one seems to lack the irregularity in color and texture of a typical cancerous mole.
You may want to just watch it for awhile, because cancerous moles tend to change. It may have always been there, and always that size. Measure it and monitor it. As usual, Mayo Clinic has some good tips: https://www.mayoclinic.org/diseases-conditions/melanoma/symptoms-causes/syc-20374884