Girls, Why would she accidentally send me a thumbs up on messenger when it's been a week since we spoke?

She was last to send me a message and I didn't need to reply. Anyway she sent me a random thumbs up on facebook messenger. It's that something you can accidentally do? Given she would have had to go down her list into my conversation and press it

Girls, Why would she accidentally send me a thumbs up on messenger when it's been a week since we spoke?
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