Hard to say. Pain on the surface of the penis, without a visible abnormality, probably doesn't indicate an STD or any significant health problem. And anything you have to use a magnifying glass to see probably isn't significant. However, I cannot say for sure that nothing is there. Tests for herpes simplex virus (HSV) itself require a visible sore for testing. Blood tests are available to look for evidence of infection, but they do not become positive until several weeks after infection.
Obviously, if a more obvious visible abnormality appears, see a health care provider; or if the pain persists for a few more days. Your local health department STD clinic would be a good bet, or your primary care provider. In the meantime, you should speak with your partner and make sure she doesn't have symptoms, and to learn whether she has a history of herpes.
Good luck-- HHH, MD