What did young Hagberd think it meant when old Hagberd said that his son would be coming home ‘tomorrow’?

Young Hagberd got a bit concerned and he was confused that if old Hangberd had identified him or not and that’s why he changed his tone from told old Hagberd that ‘You’ve

grown a beard like Father Christmas himself.’ The reason to change the tone is just if old Hegberd could not recognize young Hagberd.