This kind of stuff happens to me all the time.....here is my rant....
Boss: "I need you to do xxx right away",
Me: "Okay. Do you want me to call yyy, because they were waiting to hear from us?"
Boss: "No, I am going to stop by there tonight and talk to yyy"
Two days go by.....
Boss: "Why did you do xxx?" (seriously)
Me: "You told me to do it."
Boss: "Why would I tell you to do xxx? You must have misunderstood. Have you heard back from yyy yet?"
I am being completely serious....some days I think my head will explode!