Disclaimer: All characters belong to JK Rowling.
Albus was not the type of person who expressed all of his emotions to the world. He was a very reserved person. So when Albus expressed his joy as he ran towards Scorpius, the latter knew that something important had happened.
"Scorpius! James spoke to me!" Scorpius wanted to reply with: "Finally! It was about time!" Especially after three weeks of Albus's hard work, but he was destabilised by the huge smile that approached him. It was the first time that he'd seen him with such an expression, so Scorpius Malfoy decided to quieten his bad thoughts.