I don't even know what goldenseal is. Sounds like an herb. What do you use it for? I doubt there would be a contraindication, but if you are concerned, ask the doc who prescribed the Valtrex for you. Most herbal remedies don't have clinical studies to back up their efficacy. Do you really want to spend your money on stuff that is not proven to work?
http://nccam.nih.gov/ is a good website to refer to to look for issues with herbal medicines.
They do not routinely test prescription medications for interactions with herbal preparations. I've never read any studies that said that you couldn't use these 2 together but as I said - it's doubtful it's ever been studied.
Not an answer I know but there's just way too little info out there on herbs in general and interactions to give you a definite answer one way or the other.