history: My coworkers threw me a 20th anniversary party at work last week. I had no idea it was going to happen. Last week at work_comma_ my coworkers threw me a 20th anniversary party at our company office. Oh Wow! 20 years at your job! You must be well liked there. 
current: I like to think I am. I had no idea this was going to happen.
next: It must have been a wonderful surprise for you.