Edited:
Thanks for the responses. Oops, it seems I mostly messed this up myself then.. And it is not news to any regular forum user that Pimsleur is full of strange expression that no native speaker would use.. So I guess it was not so strange after all.
I just want to mention something fyi - "my bad" is usually not heard this side of the Atlantic! It's normally a giveaway that the writer/speaker is American!
Oh and one more thing - it is I STAND corrected.
One of these strange English expressions that don't make a lot of sense....