When we pass on, our spirit sometimes lingers where it was most comfortable (like their home) until they officially and fully cross over to the other side. This could cause paranormal activity.
You might also experience signs that the person has officially and fully crossed over – like smelling their perfume, cigarettes, cigars (if they smoked), hearing their song on the radio, seeing something that was meaningful to them (like a specific bird, butterfly, etc.) or maybe even the time on a clock or special number.
Signs are everywhere.