[LOTM VOL4] since when did Sharron?!

Am i tripping or did Sharron just call him klein?! Since when did she know him as klein instead of sherlock? Why is klein so nonchalant about it. Is this a translation error? Did i forget something major?

Am i tripping or did Sharron just call him klein?! Since when did she know him as klein instead of sherlock? Why is klein so nonchalant about it. Is this a translation error? Did i forget something major?