Sometimes a sim may pick up a teddy bear and just drop it somewhere when he/she realises it'd be better with taking a shower or a snack, so it may be in suspicious places. But then again, they're not expensive, are they?
If you find the missing teddy bear after a while it's just as simple as to delete it. Alternatively, if you do feel this is a bug and it's wearing down your fire meter, you could try to move somewhere else.