Should I bring a gift for my boyfriend’s parents if I didn’t know they were visiting?

I’m currently visiting my boyfriend in the U.S. We’re in a long distance relationship, and I live in Japan. His parents are visiting us for two days, but I didn’t know they were coming, so I didn’t bring any gifts from Japan.

Would it still be appropriate to get something for them? They are American, and I’m unsure about the cultural expectations. If so, what kind of gift would be suitable?