Short answer: Yes.
You have to check the county records from sovereignty to verify your mineral rights. The county clerk will not be able to do that for you. That’s why they told you someone knowledgeable would have to check the title. This would be a Landman or an attorney. Landman is usually cheaper. You can do it yourself if you have the time and patience for it. But if you’ve never run title before, I would not recommend that.
It sounds like you should get someone to verify the ownership of you and your brother, and any family members who have questions. You can then get an attorney to draft a correction or stipulation of interest for you and your brother so that the title reflects what you want.