> I guess it was a mix of enjoying the attention, pitying weaker students, and wanting to reward "participation".

It probably wasn't intentional, just 'I have x minutes a day with the students to teach them the day's lesson. I have more than x minutes worth of content to convey. If you willingly spend more time with me, you may get information that was lower in importance and was missed during the day's classes.'

I don't see a problem with that and is not what I had in mind with "pretty big hints". See my other reply here: https://news.ycombinator.com/item?id=47493450