you did fine.
when my oldest was very small i had to move back in with my parents after my divorce. no job, no skills, etc. my mom kept my son while i went back to school and found a job. i figured she'd done all right by me (i didn't blame my parents for my stupid teenage rebellion that got me into this mess to start with.) so i never commented when she disciplined him. he is 21 now and they have a very special relationship. he is a fine young man and did not inherit my "stupid" phase. my mom and i always backed each other up on his discipline and it seems to have worked well.
i think you did a good thing with your gs and i am sure he will remember it.