I'd just go ahead and scrape it off anyway.
I've had this problem in my 38 gal. tank as of late, and I think it could be partly an overfeeding issue, but also the fact that it is a new setup.
I use an algae scrubber to scrape it off and vacuum up any that might happen to be on the substrate. Rinsing out filter sponges in the discarded tankwater is critical too, as these end up collecting a lot of the brown crud that you wipe off the walls and other surfaces.
Just scrape it off with the scrubber. Anything else that it is covering can be cleaned by using your fingers to wipe it and/or remove it from the tank and run it under some tap water. A 50% water change would be fine, but I don't know that taking out this much is really necessary.
Hope this helps.
BV