White Spot?

I always found that my related green neon tetras got whitespot worse than the other fish.

Did the spots only last 24 hours or did you only notice them 24 hours before they disappeared and they could have been there longer, you just didn't notice? The reason for asking is the spots are usually on the fish for longer than 24 hours.

It's a tricky one. All fish medication is quite hard on the fish so we shouldn't really medicate unless necessary. But whitespot will come back if not treated.
Some people have success using just heat and others also add salt, but neons don't particularly like salt.

I think I would buy some whitespot medication (always useful to have in) but watch the fish like a hawk until you see more spots before using it. The neons will probably show signs first if it does come back.
If you do need to treat the tank, follow the instructions on the bottle to the letter. Most of them have you dosing on certain days with days when you don't dose. You must add the med when specified even after the spots have gone. And with you doing a fish-in cycle you may need to do water changes on non-dose days.
Dose days are easy - just do the water change then add the med. On non-dose days, add enough med to treat the volume of new water going into the tank.