Girlfriend's got an 07 2.0T with 51k miles on it. Recently coolant warning light has come on multiple times, checked coolant, level is fine, maybe a minor slow leak (couple of dried droplets visible on the AC lines running underneath). The warning goes off after a few minutes of driving, but this isn't really what I'm worried about.
Got back from Coffee Bean this morning and it was making some strange noises, so I poked around the engine bay. Coolant was still fine, checked oil, little low but not at the minimum, but upon taking off the oil cap I noticed this (upper rightish part of the cap mainly):
Any ideas on what could cause this? I believe this is coolant and oil mixing but I wanted to verify this before I start investigating further.