How can I touch up a marred furniture paint job?
You didn't say how large the entire top was. Over brush snagging looks terrible, unfortunately. If you really want a smooth consistant finish, don't attempt to just touch up the flaw areas. I would sand the top again, making sure the snags are very smooth, then put a thin coat on the entire top. Dust control is the key to doing furniture. If there is minor dust on the finish, leave it alone until the piece is cured completely. You can then buff if with a polish compound or ultra fine automotive finishing paper that won't scratch the gloss, but will remove minor dust flaws.