I think you're probably right in this case. However The Quiet One, a stealth helicopter based on the Hughes OH-6, was reputedly tested over Los Angeles in the

I think you're probably right in this case. However The Quiet One, a stealth helicopter based on the Hughes OH-6, was reputedly tested over Los Angeles in the 70s. An unusually quiet helicopter doubtlessly attracts less attention than a jetpack though. (Hughes was based out of Culver City in LA.)