The OP is fine. You're being overly pedantic. People have been using the word this way for (literally) hundreds of years.
Moreover, the truly literal definition of the word is from the Latin for "letter" and means something like "letter-for-letter truth." So using this word to describe anything other than a written document is "wrong" on some level. But language doesn't really work that way.
Moreover, the truly literal definition of the word is from the Latin for "letter" and means something like "letter-for-letter truth." So using this word to describe anything other than a written document is "wrong" on some level. But language doesn't really work that way.