Pianotech

Hello.  I recently saw a piano that originally had rubber head nails for bumper,  Someone replaced them with the mushroom style bumper and glued them on.  The customer said it was a long time ago.  Now those rubber bumpers have melted.  She said the piano never got hot, so I'm wondering if maybe the glue they used reacted chemically with the rubber.  This was the bumper glued to the lid prop.