Xin W cast time possibly not updating after receiving E's AS bonus

Title really. When I got my Bloodrazor enchantment my W cast time went down to .50 seconds, but when I charged a jungle camp with E and checked W's tooltip again it was still .50 seconds despite E's 40% bonus AS that was still in effect. Because this is about an approximately .05 seconds cast time I've not been able to discern whether this is an actual bug or a tooltip error, but I'm putting it up here anyway. Thanks!