The original poster (OP) clarified that his son, who received the down payment help, has been diligently saving and was recently in need due to a competitive housing market.
Check in with them now to see how they are performing in their classes. If they are doing poorly, encourage them to find a tutor and go to their professor's office hours. I've seen many students be too embarrassed to tell their parents they are struggling only to end up with poor grades at the end of the semester.