The last sentence "Je vois encore son sourire quand je l'avais surprise." I thought toujours would be better here as “encore” is more often used to describe something that's not going to last much longer, or something that's been repeated. “Toujours” expresses the fact that it's something frequent, or something very long (in this case, he will likely not forget her smile for a long time).
Could you explain why we use encore here?