Some yeasts create different krausen than others. I've used some that create a really thick goop on the top and some that create a really fluffy foam. If the beer tastes fine and there are no strange smells (beyond the normally strange smells of some fermentations) don't worry about it.
Also if it were me and I still had a krausen like that on the beer, I wouldn't bother disturbing it to take a gravity sample as it's obviously not done - but that's just me.
