was my dog put in dog fighting?

when i was younger maybe in the fifth grade my family had to get rid of our dogs because we were moving somewhere that didn't allow pets. so we posted them in craigslist. my dog was a stocky tan lab named Piper. and one day while i was at school my dad had gave her to a lady. the lady said that we could visit my time to see her but when we texted her the next day seeing if i could to say goodbye she said she ran off her leash. it just all seemed fishy to me and i know Piper wasn't one to run off, though maybe because of a new place? im pretty sure she was posted for free. anyway i never thought about that possibility until recently and now im really worried/bothered by it. let me know your thoughts