Experienced eye required

Hi guys, just signed up to try get (hopefully) a professional opinion on something I spotted while servicing my car the other day.

I was upgrading my sparkplugs when I spotted I guess 'gunk' on my high pressure fuel pump sensor / barrel area. I did previously notice it before when the downpipe was getting fitted. And I couldn't tell if it was worse or just the same but it really caught my eye on Saturday gone.

I took some snaps hoping a keen eye might advise if it's normal, bad or ugly? I'll try attach an image here. I spoke to a guy on eBay who suggested it might be fine it might just need a nick of tightening up.. 

I'm @40k miles, 2.0tfsi A4 Quattro S Line (Stage 2) 

Anyone any idea if this is just build up of gasses over time or a leak? If you too had a similar discovery. 

I haven't touched it yet. The car drive a dream, especially with the new plugs etc. But I'd rather eliminate an issue than deal with it when it arrives. My thought process was to disconnect the power to the pump, isopropyl clean the area, threads especially, then check the tension on the sensor bolt and nip it up an inch, monitor, if more nip another inch etc. 

What I'm curious about is.. is the sensor bolt high because it's torqued at that height or does it have a stop point that height or does it look too high or can to sent it too far and damage the sensor? I ask as I've not touched one before. I'd rather ask than find out. 

Any help is greatly appreciated

Damian