FWIW, if the cells are actually securely glued together, and secured inside a casing that prevents it from moving around except as a whole entire unit, it's unlikely that vibration will cause any degradation of the shrinkwrap.
However, if any cell actually did fail in a way that heated it enough to cause the wrap to split (which has happened without actually causing a fire or any other failure than killing the group of cells it's in by discharging all the rest of the ones in parallel with the failed cell), and that heat caused the contacting cell(s) in the next parallel group in series with it (either + or -) to *also* split it's wrap, *and* those splits line up...*then* a short that can cause a fire could happen.
If the cells are not really thoroughly glued together, but just have some glue on some of the cells in each group of cells that's glued to the next series group, then vibration can have it's way with the ones not secured by glue.
Same for if the glue is a type (like hotglue) that doesn't really stick under some conditions and can crack and come off.
Also same for shrinkwrap that is either already damaged or is fragile and cracks under age or various environmental conditions the pack is likely to see.
Note also that if the glue doesn't securely hold the cells in place, and they can move even a tiny bit inside their casing, then over time the interconnects between cells that can move can fracture, usually at the spotwelds, and cells in groups can become disconnected from the pack, reducing the pack capacity and capability, and stressing the remaining cells in those groups, shortening their lifespan and heating them more in use than the rest.