老板什麽意思？我要回他嗎？ 回什麽？

老板今天早上給我發了一個EMAIL， 說

I have been spending a lot of time with the .............. you worked on. I just wanted to thank you for all of your hard work and for doing such a good job on it.

前幾天他指出好幾次我哪裏做得不夠好， 今天發了這麽個EMAIL， 什麽意思啊？ 我
要回他嗎? 回什麽？