I bet they assumed your brewhouse efficiency was 75%, which is kind of an all-around average for different brewers. The "problem" might be that your efficiency is higher at around 72 * 75 / 63 = 86%. If so, that's pretty cool, you are crushing and sparging well.
It could also be that your software assumes too little extract out of each specific grain, i.e., there might be a discrepancy between the points per pound per gallon assumed by your software compared to the actual maximum based on malt brand, the season, the weather, the phase of the moon (exaggerating a little), etc. It happens.