Yes its quite possibly a spirit in your home. Children and animals are very sensitive to spirits/ghosts whatever you wish to call them. This doesn't mean that they will hurt you, 9 times out of ten and usually around children, it's just spirit children come to play, and attract your attention. They are usually connected to the house.
If you are worried about this at all and want them to move on, the best thing would be to seek out a medium or somebody that can do a house clearance for you, this way they can ask them what they want and move them on if your not happy with them being there. They are probably completely harmless.
You can also ask them yourself to move on, say a prayer and ask that they be taken to the light.