On Friday afternoon I thought the guitar sounded just a tiny bit dull and figured it was either because I hadn’t played a Negra for a long time — Negras have rosewood sides and back (dark) and produce more overtones and a slightly darker tone than Blancas, which have Cedar sides and back — or perhaps because the strings were new. So I played it Friday evening and Saturday morning and did the performance with Kaz yesterday evening.
This morning I was getting ready to practice when I noticed a piece of paper towel inside the guitar. I pulled it out, shook the guitar and saw another paper towel inside. I was able to reach it through the strings and pulled it out.
I played a chord and now the guitar sounded exactly as I remembered.
I figured the paper towels were placed inside the guitar to soak up glue drops that might fall during the repair. I messaged my friend and he replied that at least it wasn’t like leaving a scalpel inside a patient after surgery, that he thought the guitar sounded nice with the paper towels, too, and that I could keep the supplies… :-)