took me a while to see it. i initially thought to myself ''you're joking, you don't know what a sliding pin's boot is?'' lol and then i seen the dull silver tape rolled around the bleed valve. couldn't say what the problem is without looking at it, either way it's there for a reason LC. i'd seriously recommend taking no risks when it comes to your brakes, get it checked out and at worst case scenario may need the valve and nipple replaced. worst case scenario would be a new or used caliper, so don't worry