My Minecraft house keeps on spawning monsters inside?

I have a dormitory on my world. Well I'm using pocket edition. When I reached the top of my dormitory, I saw a monsters such as zombies, skeletons and spiders. I don't know if is a glitch or not.

Version: 0.8.1

Guest

Your house isn't bright enough, add more torches. Otherwise it must be a glitch. Or maybe the mosters are walking into yoour house…

Bill

There's two possible scenarios here based on the detail you have given…

1) There's a section somewhere in your house that isn't bright enough. You'll need to put more torches down in the darker sections of your home. If you're short on coal, smelt some LOGS (not planks!) to make charcoal.

2) You have an open part of your house that allows monsters to let themselves in. This can be solved by blocking the entrance with spare blocks or a door.

Bb Major

Is the place lighted by torches? If not put torches or glow stone. The darker the place is the more monsters will spawn.

Rafael