Eric wasn't far. He had made sure to stay close to Lestat's door, but not too close. Just far enough for the other vampire to work up a good rile, but close enough that he wouldn't give up in his search before finding Eric.
There was something about Lestat that really pleased Eric to torment him so. He wouldn't have been able to say what, if asked, just that it was this little ticklish spot in the back of his mind that giggled maniacally at the idea of doing things Lestat could not do, having things that Lestat could not have. One upping him. Teasing him.
As Eric felt the presence of the other come closer he spoke, he didn't need to yell, knowing that Lestat would hear him just fine.