I've noticed that Spanish is a bit tricky when it comes to agreement in copular clauses. The following sentence still caught me a little off-guard though:
El deseo de una experiencia más positiva es, en sí misma, una experiencia negativa.
I would have expected "misma" to agree with "el deseo". As written, I'm about 50/50 between thinking that this is just how Spanish works, and "misma" agrees with the trailing "una experiencia negativa", versus this being a mistaken agreement with the preceding "una experience positiva".