I'm guessing that somebody pitched it to their superiors as a free solution with all the source code they could just take over and use, and now they had to have an awkward conversation about spending some money on the author. At which point it behooved them for it to at least be as cheap as possible.
Would you be willing to share what your rate was? I think it'd be useful for other FOSS maintainers to get a better understanding of their worth.