Harry does realize that and he's quite flattered she made time for him and got him something despite being so busy. They hadn't spoken an awful lot, but Harry did really like her. He nods and smiles in both acknowledgement and gratitude at the gesture.

The quick hug is a bit of a surprise and all he can do is lean into it awkwardly for that quick moment. Before he can reply or even truly express his gratitude, she's already gone. He lingers for a small moment, telling himself he'll have to thank her again later, before moving away from the spot to put the cake away and put the card with the others.