I had this pet rat for a couple years and he died more than 2 months ago. I still hear him in my bedroom though. I don't think he thinks he's gone. I hear his little thumping footsteps and him drinking out of his water bottle and his cute little sneezing fits, but he's not there. This only happens when I turn off the lights to go to bed (because that's when he was most active). Why do you think he's stayed this long? I know I probably sound crazy but I'm not. Trust me.

His spiti came back

His spiti?

:D

I also thinks his spirit , energy is still there.
Maybe you feell pain of missing him and that's the reason its stays and try to let you know he's still there to make you feell better...
Talk to it,let him feell your love...
Whene the time is there you both know whene its time to say goodbye...