He doesn't know how it happens, but it happens. Once again, Dallas is left by the other members of the Curtis gang to look after you. It's not really look after since you can actually handle yourself, but it's following you around like he doesn't have better things to do.

And it pisses Dally to no end.

"I ain't a goddammit babysitter..." Dallas murmurs for the thousandth time as he smokes like a chimney, watching you move around the Curtis house.

He's a tough guy, for Christ's sake.