Yup - just cause they ARE wilting doesn't always mean Verticillium Wilt. You may be correct but check for swollen bine with upward curling wilted leaves.
"Wilting symptoms caused
by black root rot can be mistaken for Verticillium
wilt, Fusarium canker, or damage
caused by California prionus beetle."
"Disease symptoms vary depending
on the aggressiveness of the Verticillium
pathogen that is attacking the plant. With
non-lethal strains of V. albo-atrum, disease
symptoms often appear initially on lower
leaves as yellowing and death of tissue
between major veins and upward curling
of leaves (Fig. 40). Affected bines become
noticeably swollen (Fig. 41) and when these
stems are cut open the vascular tissue is
discolored a medium to dark brown (Fig.
42). These symptoms generally are first
recognized near flowering or when plants
become moisture stressed. Eventually, one
or all of the bines on a hill harboring the
infection completely wilt (Fig. 43)."
From PDF found on http://www.usahops.org/index.cfm?fuseaction=research&pageID=2