Kerbal Space Program

Was this your first Minmus landing? Or was it otherwise notable? If you look at the top right corner while flying, there's a list of achievements and milestones you meet along the way. When you hit new milestones, you get money and science for them. That landing might have earned science for being your first Minmus landing or first mining rig on a moon, etc.

Still sounds like a bug, but that might be the explanation.

Update: I looked inside your save file and it looks like you built a surface base on minmus as well. Making your first surface base on a body does give you science and money from the achievements I mentioned. That could have triggered it. The devs may need to update the missions to exclude science from those achievements.

I'll have to check on that. I don't think it was my first time landing on minmus but ill use the creatacontract and see if i can duplicate the results