Billy Bob Thornton is still on good terms with Angelina Jolie ... but that doesn't mean he went out of his way to get her and Brad Pitt a wedding present.
We asked him why when we ran into him at LAX on Friday ... and his reason seems pretty obvious when you think about it.
What was less obvious was why Angelina's ex thinks it would NOT have been weird if he'd gotten an invite to the big event.
Hell, her father Jon Voight didn't even get invited !
But Billy Bob's a different breed ... if anyone could pull off that inevitably awkward scene, it's him.
