Listing extra recommenders?

[gliaful]

All of the schools that I have applied to asked for the names/info of three recommenders within the application. Somehow, in my letter-requesting ventures back in September, I ended up with four letter-writers. On all of my applications, I listed all four of my recommenders. However, one of my writers has been quite busy this semester/difficult to get in contact with, and I have begun to fear the outcomes of having listed her on my applications if she does not write a letter.

 

Put simply,

1. schools asked for 3 recommenders
2. I provided info for 4 recommenders
3. one of my recommenders might not write a letter (but at least I still have the necessary 3 letters)
4. will it reflect poorly on my application if I provided info for a letter-writer who turns out to be a letter-not-writer?

Realistically, my application deadline is December 1st (for all of my schools) and she has plenty of time to submit letters for me. I'm just anxious, and evaluating worst-case scenarios often helps quell my anxiety.