i remember getting my bike brand new and it did that occasionally, it seems normal to some extent

otherwise,
maybe your spokes arent properly tightened or your tires are bending.
occasionally mine do that but not excessively enough to worry about it.
my the tires are actually pretty out of true at the moment, too, actually..

maybe you hit your disc and bent it slightly, making it prone to rub but not always.

my disc (brand new!!!!) is clearly not even but it is within range so it never really rubs.
maybe that's because i torqued it wrong, maybe that's just the variation they have.
much better than the disc that was replaced tho which always rubbed no matter what after hitting rock.