Full disclosure - I'm not nay saying the possibility of a malicious spirit, or any spirit, being involved for that matter. But if we're going to jump to paranormal we should eliminate normal causes first. Mainly with one question.

Were you waking up or falling asleep when you heard the words excuse me, or were you fully awake at the time?

If you were waking up or falling asleep, then it's highly possibly that it was a light occurrence of sleep paralysis. And kitty woke you enough to break the effect. However, if you were already fully awake, then we can assume it wasn't something like sleep paralysis and maybe a spirit.

The spirit may not have been malicious either. It could be the emotional weight of the soul that paralyzed you, and the soul was just passing through (pardon the pun).