I advise all housing users, especially the PT-59 and my own Fantasea housings (all made by AOI in China) do this.......
Take the o-ring off . After cleaning (don't stretch it!) apply a tiny amount of proper lubricant and put in a plastic bag inside your housing.
You can then fly with it, you'll see it when you arrive and install checking it slides closed easily before diving.
I had a Fantasea housing customer
CALL ME from the Caribbean after flying with his housing sealed and couldn't get it open
He put it in the refrigerator for maybe 30 minutes and voila', it opened
Any COLORED o-rings like on the Olympus housings, Sea and Sea BLUE strobe and Inon strobe YELLOW battery door o-rings, etc. should ONLY use SILICONE approved lubricant.
If you use regular Dow Corning lubricant meant for BUNA o-rings it could cause them to swell or degrade and leak !!!!!
My Fantasea housing has a BACK BUNA o-ring and WHITE inside flat GASKET sealing the door like a flat GoPro housing. Only the back BLACK BUNA o-ring needs lubed so it will close easily and not twist, roll or pinch. The from flat WHITE "gasket" never needs lubed or removed as the face of the clear housing door simply "crushes" it.
This is one reason I really like the Fantasea housings.
Unfortunately the AOI Olympus PT-59 / 60 housings only have a rear door SILICONE o-ring. But if taken care of and lubed with the proper SILICONE o-ring grease work fine.
Good luck !
DH