Feanor would not question whether the "cat" is really a cat. The term might as well be the best approximation of what the creature is.

"I'm afraid I haven't seen any creature that fits your description."

The platform is definitely too small for anything of any substantial size to get lost within its limits. The gate though... maybe it snuck out.

"Do you remember it being here? Or did you lose sight of it before you found yourself on this platform?"