Probably just a lucky fluke on your part. Happily take the free rating points and move on.
People randomly resign for many non-chess reasons. Maybe they have an emergency and need to leave. Maybe there are distractions and they can't think straight. Maybe they are under age 18 and their parent(s) called them for dinner, or told them to get off of the computer.
We really don't know why people resign, but it is better they resign than abandon the game and force you to wait on the clock.
What is for sure is that most people don't resign this early, so just take your free rating points (and rejoice!) and especially as you climb the rating ladder, then people will take chess more seriously and resign much less often for non-chess reasons.
Players resign when we are only a quarter way through the game- no one is winning. Most of the time, they have the advantage- but they just resign. Is it because I'm not worth it- or they don't have the time?