So - yesterday I had a crew clean out the gutters and remove all the debris on the roof from all our spring storms. The sound of feet & voices on the roof spooked the cats - esp. Stella. When I got home, Stella continuously paced the rooms, opening cabinet doors and looking behind room doors - to make sure those loud voices were gone. When I went into the bathroom for my shower, she raced ahead and looked behind the shower curtain at both ends - before allowing me to take a shower. She was still rattled, but wasn't going to risk my life by letting me enter an uninspected bath tub.
She is part dog, and - for a cat of her size - quite timid around strangers.