The voyages were long, and your biological age would end up getting shifted compared to your actual age.
Mira bothered accounting for interstellar time dilation in a smut story? Now that's dedication.
That's also one of the wait-what parts of the setting I mentioned, as time dilation being actually relevant implies interstellar travel slow and inconvenient enough to render the whole premise of shipping bulk raw materials over such distances quite ridiculous. Just mine your local system of reference instead - plenty of stuff in the asteroids and whatnots, jeez.
To speak nothing of that half-baked mine scavenging business in the same context...
I have no idea how time dillation works. Does faster than light travel make you older or younger?
It's one of those things involving special relativity but to simplify it. When you go really fast, like approaching the speed of light fast, time goes slower for you and faster for everyone else so you travel forward in time. The faster you move the further forward in time you go which makes it look like you don't age while the rest of the universe does.
It doesn't really become relevant till you've been traveling at, at least, half the speed of light for a few decades though.