I wouldn't be so uppity. It was an error and they fixed it.
LOL, not sure what's "uppity" about that comment.
My guess is that most people would have a problem with Marriott changing the pricing on a confirmed reservation without their consent or notice and the fact that Marriott did it in this case suggests that they can do it in others. If it's being "uppity" to be concerned about this, well then ... I guess I am uppity.