Look's like something has upset Taeyeon which made her give a sulky expression. On the 11th of March, SNSD was spotted at a department store for an autograph signing for J.Estina which is a brand they are advertising.

On the autograph signing, Fans spotted Taeyeon making a sulky expression as if she was upset about something. Netizens commented, "What made her mad?", "She looks upset", "I hope she's not so upset".

Source