It's more likely that the small scab on your lip is due to an injury rather than herpes. Herpes typically presents as a cluster of fluid-filled blisters that eventually burst and form shallow ulcers, which can be painful and accompanied by redness or swelling. Since you've never had a cold sore before and there are no other symptoms like pain, it seems less probable for this to be caused by herpes. Keep an eye on it though, just in case any changes occur! If you have concerns about STDs or need further clarification regarding herpes symptoms, feel free to ask!