Little did he know that his handwritten thank you note would become a viral Internet sensation.

Why? The woman to whom he wrote the note was Australian actress Claire Holt, who took a picture of the note and tweeted it to her more than 700,000 Twitter followers.

The tweet read: "Wow. Received this note from Captain Kendall on my flight today. Truly thoughtful. Treat him well @DeltaAssist!"

According to Yahoo, Holt is best known for her television work in "The Originals", "The Vampire Diaries" and "Pretty Little Liars."

Delta Air Lines confirmed to ABC that Kendall, a 25-year Delta pilot, wrote the note.

According to the ABC story, Kendall did not know Holt was a celebrity, only that she was a serious frequent flier.

Diamond status is the highest level of frequent flier membership in Delta's SkyMiles program. It requires 125,000 miles flown per year.