Anyone else's little suddenly afraid of the dark?

He's always slept great in his dark room with blackout curtains and glow-in-the-dark stars on his ceiling.

He's recently been loving "spooky things" and getting super excited about Halloween (decorations, costumes, etc.).

We just got home from vacation where the four of us (4 month old in a pack and play and 3 year old in a cot) shared a room.

Putting him to bed in his room tonight was terrible and he cried for an hour, not wanting us to leave.

Has this happened to anyone else? Did a nightlight actually help?