Flight specials

Yesterday I searched the web for tickets from Bloemfontein to Cape Town return. Travelstart had tickets for R660 pp one way. Just above the amount of R660 was a blue box which said "2 days left". I did not book the tickets because there was 2 days left for the special. Today when I want to book the tickets, the special was not there. I had to book tickets for about R900 more. Why did they say "2 days left"??