Underlining of correct grammar contractions
When I type contractions—such as didn't, couldn't, wouldn't, shouldn't, doesn't, and many other simialr contractions that have the word 'not' in them—they are underlined. I am pretty sure that such contractions are correct grammar, but I don't know why they are being underlined (with the red dotted line) indicating an error or mispelling. This happens in some of my applications, especially WhatsApp, and it doesn't happen in Messages and Notes. It only stops when I turn off 'Check Spelling' in Keyboard Settings, but I have asked two other people—who also use WhatsApp—about this issue; they have all of the Keyboard Settings turned on (including Auto-Correction and Check Spelling) and they don't experience this issue—I am not sure if they checked correctly though.
Are there other iPhone users operating on iOS 7.1.1 experiencing similar problems? I have an iPhone 5s on iOS 7.1.1.
Is this a bug or it's normal?
Hoping for feedback. Thanks.
iPhone 5s, iOS 7.1.1