Sookie may not be sensible in regards to herself all the time (no sense of self-preservation, as he liked to point out), but she does tend to be sensible about the well-beings of others, and that includes vampires -- especially her vampire boyfriend. While no-one's shown up yet that could do Eric any real harm, the fact that someone could with the right sense and know how scares her. Just a tiny bit. She's seen what drainers and a bunch of rabid wolves have done to Bill, and while Eric is older and stronger and faster, he's still vulnerable to silver and can be taken down with enough of it.
Clothes burnt, ashes dumped back in the pail, Sookie shed her clothing and headed into the bathroom.
"Scoot over," she told him, motioning for him to make room for her in the tub that wasn't exactly made for two.