How was she other then the peeing incident? No biting or anything?
Is she littler box trained at all? I never had any trouble with my boy peeing on anything weird like that, he always went in the same spot in his cage and absolutly REFUSED to go anywhere else. I think you had mentioned that she had peed on this couch before? Maybe that's just the spot she chose to go to the bathroom, and the other day you just happened to be in the way, lol.
If I were you I would try to get her box trained. First of all, wash the couch as good as you possable can so she can't smell her sent on it. I googled your problem a little since I've never really had that problem and found this...
"One thing I don't think it mentions is a technique for training a rabbit to stay off a particular piece of furniture they've decided to make a toilet. It's a pain in the butt for a while but many people find that it works. Get plastic sheeting (not thin like garbage bags, but thicker stuff like a dropcloth) or an old vinyl shower curtain and drape over the couch. When he jumps up on it, he will probably not care for the crackly plastic feel of it rather than the soft fabric he likes. And if he does pee it protects the couch. The idea is you leave this on the couch whenever he is out for a few weeks and he gradually loses interest in the couch, and you can take it off. Some people add aluminum foil for that extra touch of crackly uncomfortableness. This is not guaranteed to work but it's worth a shot"
That might at least protect your couch! As for the actual litter training process itself I'm going to direct you to the house rabbit society's website again, they have tons of info about it that should be helpful!
Here's the site, just copy and paste it into your browser...
http://rabbit.org/faq/sections/litter.html#method