A320 STRANGE PTU behaviour
737 jock, it's not the ECAM inhibit that has been modified to present a HYD SYS LO LVL on the ECAM below 1500ft/2min after lift-off. The PTU inhibition logic mod has been applied to all ezy airbuses. This means that the PTU will not run when either HYD SYS LO LVL to protect against an inadvertent overheat due to PTU overspeed as you stated.
Getting back to the OP. I have found the PTU to run many times as described, albeit not continuously. Surely the 'AUTO conditions to run' were not met at this time. I attribute it to a 'glitch' as you said and nothing to worry about when all other indications/ops normal.
ATB