Dad and my forged signature

We could all remember the funny aspects of Dad like him yelling "Doooooorthy!!!!" at six a.m. and him leaving the bathroom door open whenever he would use the restroom, but there was one instance where Dad showed his true parental side towards me. I was in the eighth grade and I got a C- on a History test. Unfortunately for this class a parent signature was required for all tests under a C. This was the beginning of a new quarter and Dad just yelled at me for my previous report card so there was no way I was showing him a C-. I had no choice but to forge the signature. The next day my teacher looked at me and asked me "Who signed this?". She told me that I was going to talk about this issue with the Vice Principal the next day so I had to tell Dad about the test and his forged the signature. That day I went up to Dad's room to see him sitting there with his thick frame brown glasses sitting Indian style on his bed reading a some programming language book. I told him about the C- and forging the signature to obviously get yelled at, but he also told me that he would tell the principal that he signed the test so I would not have to go to Saturday School. Due to the lack of precision in the signature I was forced to confess to forgery and I was Saturday school bound. They called Dad and told them that I forged the signature and I talked to Dad on the phone while sitting in the office and in these words he said "You know what I am proud that you told the truth so now you have to face the consequences for your poor decision." Every other time I got in trouble before and after this issue his reaction to my problem was anger, but I still to this day wonder why his reaction was so calm and collected for the forged signature.