You need to define "Spring assisted". Yes, I understand assisted opening knives vs switchblade knives. Just be sure Officer Friendly understands.
Federal Statue 15 USC § 1243 provides, in pertinent part:
Whoever, within any Territory or possession of the United States, within Indian country (as defined in section 1151 of title 18), or within the special maritime and territorial jurisdiction of the United States (as defined in section 7 of title 18), manufactures, sells, or possesses any switchblade knife, shall be fined not more than $2,000 or imprisoned not more than five years, or both.
And, yeah, Guam falls into that category.