Trent,
I typically will refer my client to the EPA for authoritative information to let them determine the significance of it. This is something that I may say in my report.
Refer to the following web site for information regarding Vermiculite insulation found in the attic floor:
http://www.epa.gov/oppt/asbestos/insulation.htm
This type of insulation has been known to contain asbestos. Based on information contained in the web site, further investigation and remedial actions may be warranted.