Brake Fluid Leak ? - Both Rear Wheels ?

[rcscs1]

Hi,
Washed car at the weekend, alloys a little dirty but nothing unusual noticed.
Drove for about 20 miles (fairly spirited but I don't recall any heavy/sudden braking).
Next day I notice that there is a fluid link 'ring' around the inside rims of both rear wheels.
Pictures attached (hopefully) - anyone have any thoughts what this might be ?
Presumably this is brake fluid but why would it show up on both wheels simultaneous ?

Any info/insights appreciated...

[Ewazix]

The chances of blowing a caliper seal or hose connection both sides simultaneously are minimal as they are on different pressure circuits.

You say you washed your car, as you know the discs form a layer of rust withing minutes of washing, the only thing I can think is that the thin layer of rusty water has splashed off the pads, or maybe a cleaning product residue. Did you used a wheel cleaner?

....... or someone HAS jiggered your brake lines, did you upset someone?

[flybobbie]

I have seen the same after rain, it's just dust washed off the discs.
The caliper looks covered in dust.
Plus the discs rust quickly so some could be the scrapping of rust off the discs.