Hey @Faizal, your worry is obvious in such sensitive situations. To check if your file was ever encrypted, open is using any of your favorite editors.
vi filename
If it shows gibberish then its encrypted(lol until you've stored some gibberish data).
ansible-vault edit
The following command decrypts the encrypted file and then opens for you to edit. As soon as you close the editor it automatically re-encrypts the data.