If they'd already granted you permission to email them, you should be in the clear generally speaking. Bear in mind that if several of these members haven't heard from you in awhile, and have since decided they don't want to receive your emails, you may get a high number of unsubscribes or even spam reports from them. It's also possible that some of those addresses are no longer valid, resulting in higher bounce rates as well.
Of course, I encourage you to confer with our email permissions policies (including anti-spam policy) when it comes to emailing lists you're unsure about. Otherwise there's nothing explicitly about using "older lists."
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ William A Community & Social Media Support