It is yeast. Don't worry about it. Rack under it and all will be good. 05 is very similar to Kolsch yeast. Kolsch yeast is sticky and gooey but it rocks.
Yup I have a 2L starter going right now with S-05 and the top is covered with yeast.. it's also stuck to the sides. I'm pitching this bad boy in a few hours so i'll use a sanitized spoon to scrape it of the sides so I get all the yeasties in my wort! :rockin:
About 3 years late to the party here, but I had the same issue with us-05, I have used saf-04, saf33 and nottingham before, and they all looked slightly different, but all more foamy and less viscous and "slimy" looking.