Wait I've been building my mod with 1.0 and not the nightlies. Does this affect the mod?
Old mods should work as before, but newer mods may use some functionalities that were introduced in the nightlies. Mostly TFTD stuff like the drawing routines, but also for example the ability to modify just one stat of a vanilla alien without needing to list all other stats too.
As a modder, I generally don't require the players to use nightlies, and when I do, there's a clear information. However, this is getting so complicated that I may forget what was in the 1.0 and what was introduced later, so it's best to use nightlies.