Is this a serious problem? Someone help?

I replay stuff over in my head all the time,Like if i went to a party on a friday night i would lie in bed for hours after replaying the whole thing,As i went through the door the people i talked to.Then ask myself should i have done things different then go over the party with me doing things differently :( What the hell is this.I cant get to sleep for hours because my head is in overdrive.Is it just me?