Do I need to file an amended return 2017 if the error is from IRS and I believe

I am aware of an issue with my 2017 return only last month in March. Based on the transcript it said "Math error". I tried to review my return multiple time and still do not see any error and I noticed that IRS did not apply Foreign earned Income exclusion to my return inspite of me applying it.

 

in this case do I need to file an amended 1040X or just preparing a letter explaining my findings?