Should a new rear wiper squeak (2006 Scion xB)?

[Stuck in the Middle Ages]

I had a few things done at the dealer, and one was replacing the very squeaky rear wiper. Afterwards, it still squeaked and has continued squeaking the past few months. It also streaks like the old wiper. Does this sound like the old wiper might not have been replaced, or is it impossible to tell?

I've driven three thousand miles with the new wiper and realize I should have raised the issue as soon as it came up, but it didn't initially seem like it was worth another 30 minute trip to the dealer but now I'm going to see the dealer about another issue.

Thanks.