Small painless red patch on bottom lip that is slightly raised?

Probably sun. The most likely explanation is sun/UV light exposure to normal small salivary glands in the lips causing a small amount of inflammation. Because it is painless It is much less likely to be a cold sore due to the herpes virus. I believe it should resolve on its own. Keep your lips moisturized with use of an OTC lip balm. If it persists or more develop, consider consultation with a Dermatologist.