Exact thing happened to me one year, the nest was made of pink insulation and the 2 residents were sleeping peacefully until I scared them out of their slumber. I now always take the seat off and bring it inside when I store the bike. This is good for the seat too since the cold temps can lead to the vinyl drying and cracking.Went to hook up a trickle charger and discovered somebody installed a mouse's nest in the storage area under the seat. I was a bit freaked out so I didn't think of getting a pic until after it was cleaned up, sorry. Must say it's my least favorite farkle ever.