What did referee do during Salah's goal against Bournemouth

Yesterday night was remarkable for Mohamed Salah as he begged a hat-trick in Liverpool's 4-0 win over Bournemouth. And the win earned Liverpool 1st spot in Premier League table as Manchester City lost 2-0 in an away game against Chelsea. After Salah's second goal, the referee Lee Mason made a reaction which caught Liverpool fans' eyes. The Reds fans think that the referee was also happy for the Egyptian's goal. https://twitter.com/_MichaelGR/status/1071580777907978241 https://twitter.com/bestformofwit/status/1071780089279467520  

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