It's also a fundamental notion of science or any practice of gaining knowledge based on observation. You can't know for certain your perception is reliable, and you can't know for certain any observable phenomena is indefinitely repeatable. We don't know for certain gravity wouldn't just start working a different way tomorrow. A law in math can be proven, but a law of physics isn't known to be consistent outside of the exact conditions and times it is experimentally demonstrated, and even then only as much as you can rely on the perceptions of the observers and their account, and only to the level of precision the tools used afforded.

However, it's also not a super important consideration. In any empirical field it is just handwaved, for every conclusion you can think there is an implicit caveat it can only be taken as far as you can take the above, but nobody is adjusting their retirement portfolio or modeling the weather over the consideration gravity might change for no reason or that their own perception of the world around them is incredibly flawed.