I think that their answer of an impending power steering pump failure was correct. The reason: I had a 1982 Celica stripper that did not have power steering. I’m pretty sure that is why someone traded it in when it was only a year old. I owned it long enough to go through several sets of tires, and each time I got new tires, it felt like I had power steering. As the tires got older, the steering effort would increase, but so gradually that I didn’t notice until the next set of new tires. I think the new tires decreased the load on the power steering pump.
You should call back in a year to see if the noise has returned.