Was this manuscript supported by ANY NIH funds? AND was it subjected to Peer-Review (not subject to editorial review alone)?
The federal government of the USA is working to ensure that all scientific research funded by taxpayer dollars is accessible to the taxpaying public. As such, all papers supported by federal grant money are required to be published with some form of open access. For the vast majority of papers published from labs here at CSHL, that means navigating the NIH's Public Access Compliance system, through their NIH Manuscript Submission system, or the NIHMS.
Any papers matching these three (3) criteria must address Public Access Compliance:
Given that April, 2008 was over a decade ago, it is safe to assume that criteria #2 is met for all future publications. Therefore, if you are a researcher, or scientific administrator acting on behalf of one, and the manuscript you are dealing with was funded with any NIH funds, and was peer-reviewed, you MUST address Public Access Compliance.
The only area where this becomes somewhat in question is the case for review articles, which in most cases are not peer-reviewed, but sometimes may be. If you are unsure in the case of your particular paper, please contact the editor at your journal to determine the answer.