why does this keep happening to me?

For some weird reason I sometimes know or hear things before they happen. For example I was just in the living room watching t.v then I hear what sounds like my sisters car pulling up. So for a few seconds I watch t.v then get up to open the door for my sister. When I go outside there is no car there. Then I'm like I know I heard a car and then two seconds later my sister pulls up into our gate. When I told her what happened she says that she just pulled up and that she didn't know what I was talking about.