fluid leak inside Aer Lingus 330 - what?

My sister flew DUB-SFO on a 330. She was in the second back seat. Fluid leaked on her feet during the flight. It was black, oily but not oil, maybe some sort of hydraulic fluid. I can’t imagine what sort of fluid can drip down from under a passenger seat. Anyone got any ideas?

Guinness?

unlikely. She’d have licked that off.

So was it her seat (#2) or the one in front from which the leak came?
Are you sure it was SFO and not SFX for EIN 330.
She should be glad it wasn’t the AB 330 (N220FR) that went into Dallas on 10/13!

Bravo!