It is consistent, but could still be a problem. When you open cans of ammo like this after long storage, place the can on a surface that will ground it. Avoid sources of flame, spark or static discharge.
Aafter you have removed the ammo, aired out the can and inspected the ammo, you can again repack it in the can.
If you store powder for long periods, you should inspect it similarly.
It would be a very rare and freak accident that could cause you trouble, but why take a chance? Even a small pocket of ether gas will flare if it receives a source of ignition.
One of my best friends walked into a powder magazine and (investigators thought) a source of static electricity ignited the fumes in the air. They didn't find enough of Steve to bury.