The Girls Aloud bandmates hadn't spoke ''in forever'' but Cheryl tweeted fans to ask them to name their favourite songs from her albums and Sarah got in touch, with the pair sharing a heartwarming exchange.
Cheryl wrote on Twitter: ''Yoo hoo can you tweet me the songs from my albums that you think should've been singles please (sic)''
Alongside a thumbs up and heart amoji, Sarah replied: ''Hey stranger!... U know FFTL will always be the one #TrueToTheGame (sic)''
And Cheryl replied with a heart and kiss, soldier, and dancing lady emoji, alongside the hashtag ''#alwaystrue'' and a winky face.
Sarah won 'Celebrity Big Brother' last month and when she first entered the house it was rumoured that Cheryl was worried the troubled star would discuss her personal affairs and their supposed feud.
And although Sarah vowed not to talk about her former band members - also including Kimberley Walsh, Nicola Roberts and Nadine Coyle - she said the 34-year-old singer ''meticulously'' managed her pregnancy in order to get the maximum publicity, and also hinted she'd had a falling out with Cheryl despite being once like ''sisters''.
She explained inside the famous abode: ''I'm only 5'5'. When I wear heels I'm a lot taller and I always looked the tallest in the group. I looked like a giant next to Cheryl. She's like a Polly Pocket. She's very petite. I haven't spoken to her in a while.''
Asked whether they'd had a falling out, Sarah - who recently admitted to having a ''mini-meltdown'' every four weeks - said: ''Everyone asks that but we're so busy with our own stuff. It's not for me to say.
''Honestly, it's not for me to say. I don't like talking about the other girls if it's a personal thing. I mean, we were like sisters, so of course it would never be plain sailing the whole time. Being around girls all the time is difficult, you know?
''Nothing lasts forever. We went through so much, even if had fallen out, I'm sure it wouldn't be a major deal in the future.''