this is a dead topic that I missed...
Deja-vu is nothing but a slight misfunction of our brain.
Here it goes:
When you see/do something and that your brain decides to record the event in the old memory instead of the recent memory. So you have the feeling that you've already seen/done this thing, but it's wrong...

I used to get it really strongly all the time when i was like 13/14.....i put it down to hormones and the like

Whoooooa, I'm getting dejavous just seeing this thread again.....

haha