Because I'm still a temp, I have to fill out a weekly time sheet. I'm supposed to put when I come in, when I leave and how long I was gone for lunch. Then I'm supposed to total everything up and put how many hours I worked that week. My first week here was only 3 days and it was the first sheet I had filled out. I was rushing, trying to get it filled out before my boss left (he had to sign off on it). Somehow I missed the part about taking out lunch. So I was overpaid by 3 hours.
I feel like I need to tell my boss, but I'm really terrified for some reason. The accountant is super scary (she has grabbed my arm a couple of times when I was about to do something wrong) and I'm afraid she's going to eat me alive

Please tell me it's not as bad as I'm making it out to be?
ETA: The paycheck comes from the temp agency. I assume they 'charge' my company each week/month for what I'm paid. So I probably have to tell my recruiter too.
"In the old days my ass would be in your back yard picking cotton, so excuse me if I don't put much stock in how f*cking awesome the old days were." -Nuggs