I don’t know when this started looking like this. It wasn’t there in July riding in Colorado. I rode this past weekend pretty hard for 3 days (Adventure Palooza in Missouri) and noticed this “stuff” while cleaning my bike up yesterday. I sucked it out of the reservoir and put it in a clear container. Initially milky (i.e., the substance seems to mix with the brake fluid) this morning it has separated again and it looks like it did sitting in the fluid reservoir. Of note perhaps, after I removed the screw on reservoir cap, I noticed the rubber insert was misshapen (kind of folded up on itself) It’s time for fresh brake fluid anyway. Just curious what this is.