The D1.5 restriction means that yes, the test expires 60 (or 36) months after it was performed.
There's not a whole lot of justification for it. There has been discussion of removing it. But there's paranoia about removing it.
The only reason I could think of to keep it is that it's possible that the formulation of the consumables might have changed just a wee bit over the years, not enough to change classification, but enough to change performance.
My prediction is that the non-fracture-critical limit (60 months) will be gone by the next D1.5 edition or the one after that. Fracture-critical (36 months), less likely.
Hg
p.s. Note to those who recognize me: I disagree with the requirement, but I plan to continue to enforce it; I go along with the AWS democratic code-writing process. So don't get any bright ideas.