The pair has only recently started talking again after Cowell dropped Cole from the judging panel on the US X Factor. But according to The Mirror, Cowell spotted the banner flying over South Beach on Friday and found it hysterical. It read 'Simon Cowell is 52 today! Ha ha ha! Love Cheryl xoxo.'
'Simon has always loved her sense of humour,' said an insider. 'Cheryl knows he likes to keep his birthday quiet so he thought it was very funny that she was teasing him over it. They had a strong friendship outside of work.
'The past couple of weeks they have been back in touch and there's no doubt they missed each other's friendship.'
She also took to Twitter to make sure that Cowell's birthday would not pass unnoticed.
'Simon Cowell is 52 today. Ooops... I don't think he wanted that mentioned,' she wrote, adding, 'He is officially in the overs category... Hehehehe.'