Brown algae is very common in newly established tanks. Many will see it come and go over the first 3 to six months. At worst it is unsightly, though not harmful.
As for your question of cleanup on, you should be able to simply wipe it off the leaves. Gently with your fingers or a soft toothbrush should work.
I tried getting some of it off last night and it came off quite easily. A soft toothbrush might work also, I'll try that. The leaves are just so fluffy and gorgeous I don't want to snip them. Might get an Oto or 2 to help also...thanks!