Yeah, HP is relatively safer than FM, but because it's one of the MP events that's generally safe, it's easy for people to get careless and forget that only 2 HP are needed to be sorted into a group.
There are many ways you can accidentally get house points through the main story and TLSQ/SQ. If you know the drill, that's good. But sometimes, others need a reminder. Still, we don't know for sure if it's a regular event or a MP event or even no event at all. As for me, I always avoid playing around the times when events are usually launched. It's become a habit now.