Fungus Identification can be really tricky. Could be brown patch, could be dollar spot, summer patch,pythium blight and others. Look to see if there are lesions on the leaf blades and what they look like.
These fungus also effect different grass types. Brown patch only affects tall fescue really. I'm not sure if Kevin has Tall Fescue, he might have kentucky blue grass? Hard to tell from those pics, maybe it's a mix of grasses.
I was going to say the same as SJones, doesn't look too bad and just monitor it. If it spreads like crazy then maybe think about an action step.