you were doing your task at the vault in the airship,you heard someone got out of a vent and then shapeshifted themselves to their normal form,they started to notice you as they know that they got caught and then quickly made his mouth invisible

They are a white coloured shapeshifter impostor with a yellow visor with a ":)" drawn on it and spring antennas with red circles on the edge.

"O-oh uhm hi there,you didint see anything here heheh.." He tries to act cool with it