I think there's been a lot of over-reaction for moms actions in previous chapters. She just wanted to encourage her elder son to do the best he could at the time. Now she recognises that it wasn't a good way to go and is regretful of the way she was. Also the son recognises that what she was doing.
I had a few incidents of my own in a very similar way, I get that my parents wanted the best for me, but weren't very good at communicating that, perhaps it was due to the way that *their* parents were involved with them.