I am very familiar with DSLs but had not heard them called "little languages". I cannot say I find it fitting as it makes me think more of languages with reduced syntax or semantics.
It seems to be making a comeback though! I prefer it too. It's not really more descriptive than DSL but it's not much less, and is less jargony and just cuter.
The AWK Programming Language, 1988, Chapter 6: Little Languages
https://archive.org/details/pdfy-MgN0H1joIoDVoIC7/page/n11/m...