Do your cats "see fairies"?

TommyJack was watching something lastnight, not moving his eyes but his entire head. He'd look at the floor, along the floor, up the wall, down, back to the floor, to the other side of the room, darting his head. I didn't see anything and we weren't messing with him, asked the hubs, he joked that it was fairies. Later on, I found him sitting in the bedroom doorway like a weirdo, he saw something moving along the corner. When he looked serious about finding something, I pulled the rug up a bit and a yellowish spider jumped out! I freaked, the hubs came with a glass to contain it. Eventually TommyJack ate it. I know what he saw in the living room wasn't a spider. He was not himself Monday, himself again Tuesday morning and afternoon, then got weird in the evening. Here's a pic 'cause he's so cute. I tried getting video of the behavior, but the hubs kept distracting him - why do that when he's doing something cool?