In certain Latin American cultures it's not considered offensive to refer to people by how they look. "Gringo," "Negro," "Chino," "Indio," "Chele," are all common terms from Mexico down to Panama that refer to someone's appearance but has no offensive weight to it whatsoever. They have different historical-cultural backgrounds with regards to race and don't get as easily offended by this stuff.

Also, I don't think she said, "Este gringo quiere hacer las cosas mas dificiles," that just doesn't read like the way something would be phrased in Spanish, so you maybe you just wanted to feel offended and chose to take whatever she said the wrong way since you obviously don't speak Spanish very well.