Spike hadn't so much been avoiding Andrew as... well, okay, he couldn't come up with a good excuse for it. He had been avoiding the kid. Which was odd, because he usually didn't feel awkward after sex, even sex with a friend (and he did consider Andy a friend). But this was a special circumstance. He couldn't help feeling guilty, like he'd taken advantage of Andrew in a way. He had used the guy to get his rocks off -- and to screw with Angel, which was even worse. Angel might have deserved it, but Andrew didn't. All Andrew had ever done was be a friend to Spike, and he didn't deserve to have that trivialized by a drunken one night stand.
So he was actually almost glad when he saw the kid coming around the corner. He could've easily run away -- Andrew gave him a perfect opportunity by hiding after he noticed Spike's presence -- but that wouldn't have been fair to either of them. They needed to get over this and move on. He peeked around the corner, managing a small smile when he found Andrew. "Don't worry, I won't bite," he promised.