"Muelle" comes up in a poem by the Mexican poet Pedro Serrano. The context is: "...el conejo en el césped húmedo / salta y muelle su curvatura".
Can "muelle" be the 3rd person singular form of "mollir" or "mullir" in Mexican Spanish? "Mullir" is defined as "ahuecar una cosa con las manos par que esté blanda y esponjosa", which would seem to make some sense, but the 3rd person sg. form is given as "mulle" everywhere I've looked.
I am not familiar with Mexican Spanish.