Can buyer sue me for selling a car with unclean title, even when full history was disclosed?

During the buyers inspection, test drive, and again when they purchased the car I provided the following documents: CarFax report, WA state title, all receipts and records of repairs/inspections in my possession. When asked if the title was clean, I explained that the car had been totaled by a previous owner and presented the CarFax. When they tried to register the car in OR, they were given a 'salvaged title' and are threatening to sue, claiming I hid this from them. There was no indication on the WA title of the car being 'salvaged', 'rebuilt', or tarnished in any way, but I disclosed everything I knew about the history (which seemed to imply otherwise) and never claimed the title was clean. Could they actually have a case against me?