They said it could be found if like specifically looked for or something? But wouldn't show up in a background check? Couldn't find a lot of information on a legal "warning" online
As a former police officer, we could write warnings, but it was not anything that was recorded like a citation or arrest.
The people who wrote you the warning may could try to find it, if they caught you drunk on VA property again, but that would be hard unless the warning was entered and printed out using a computer.
If you had something hand written there's even less to worry about honestly, I think your good. That's the whole point of a "warning," to warn, not to charge.