That is perfectly normal, called oil snot. The filler and PCV location cause this. It is worse in winter and when making short trips. I would recommend you change the PCV valves every 25 K miles to ensure the PCV functions OK( part is 5$) and run synthetic. If the snot bothers you, just clean it out when you change th oil.

 

This is probably nothing to worry about. I'm guessing that you drive on short trips? This is a relatively common issue, and is due to moisture accumulation in the crankcase. When you drive on short trips and don't allow the engine to get up to normal operating temperature (especially in the winter), the pcv valve doesn't vent the moisture. The moisture goes to the highest point of the engine, which is the filler spout, and mixes with the little bit of oil that is there. If you pull the dipstick and find it milky, that's really bad news.