Ha, I think you're the first. Good thing it's in the editable text and not on anything permanent.
Overall I think there have historically been very few spelling errors with PD, and the only long term one that comes to mind is the stock "ballon.jpg" image that came with versions like PD13. That misspelling is also present for different balloon images in several older contents packs and even the newer Graduation Pack, but most people wouldn't even know unless they looked for it.