The Steipler once made a surprise appearance at a bar mitzvah seudah to which he had not been invited.  He wished the father “Mazel tov,” then sat down next to the bar mitzvah boy, spoke with him for a very short while, and left.  After the Steipler left, the bar mitzvah boy explained that several years earlier, the Steipler had seen him enter the Lederman’s Shul on Yom  Kippur carrying a large sefer, which the Steipler assumed was a gemara.  He told the boy, “Yinge’le (young boy), now we are to daven; learning is for later.” The boy then showed the Steipler that he was carrying not a gemara, but an oversized machzor.

The mechilah (forgiveness) of a kattan (boy under bar mitzvah) is not valid, so the Steipler made sure to find out when and where the boy’s bar mitzvah celebration would be held, so that he could ask forgiveness at the first opportunity. ~ 5 Great Lives