thanks for the feedback, useful

Are you sure this isn't just the mycelium reacting to the water it all of a sudden has via the straw filled with watter. All other cakes I have seen that use this method get the same growth on top just like that.

Yer fine, more air exchange. Fan it 2 or three times a day.  You are gravy baby, don't throw them out!

All I see are dragons. Wonderful, wonderful, dragons.

its overylay buddy, cobweb mold is not that dense. more fresh air exchange should keep it from getting too out of hand. 

the straw is for distilled water.......my friend uses the same technique and always gets good results

Are you trying to grow a popsicle?
From my limited experience, that looks very strange for mycelium.  I hear cobweb mold spreads very quickly, so it might be a good idea to quarantine this specimen and give it a couple days while examining its growth rate.  If your cake has turned into a big cotton ball by Sunday then I think you'll want to toss it.