Our students christened this ball "PACMAN" after a fairly interesting failure...

On further inspection, the two halves were never properly fused - there's areas at both ends of the "mouth" where the plastic doesn't show any form of damage.
Has anyone else seen this? So far it's 1 out of the 12 FUEL we've opened and examined.
EDIT: Note, this is *after* some use - it was unfused in 2 places as shipped, then
Also, my students saw this post, tried to comment, and then gave up when they needed to "register".
Apparently I should be on Instafacetube, that's where all the action is.