Got my first paid customer in a weird way.. (I will not promote)

Hey guys, I recently left my full time job & started building my open source consistent character platform which has it's own gen engine & all. In short: One character format that works across different open source models. that was a huge hit, lot of feedbacks, 550+ stars on Github under two months so I decided to publish a cloud version for this. It has around 300 users, mostly free ones. There were no paid users till last week so I sent an email, whoever ran something to share their feedback. Soon a customer returned & paid $25, which is not even a smallest tier, then he is gone & haven't came back till now & not even replied to the email. I am just wondering what does that mean. I am just hoping that he will come back, but it's just so strange. Can anyone explain?