Again, it is a game of odds. The odds are that only 1 person, in the scenario you list, out of 999,999 will have any additional action.

The only way that you increase the odds of more action are thing like:
Being on probation/parole
Having a prior conviction for sales/transportation for drugs
Having a significant criminal record (ie multiple misdemeanors or a couple of felonies)

Even with any or all of those things the computer that tracks siezures is limited to use by customs and immigration (ICE). This works in your favor because someone would have to take the time to look through NCIC/CII (the criminal database) AND the ICE database to cross referrence. Now if you start racking up too many siezures, no matter how small, you greatly increase you odds of LE contact.

It is a game of odds, nothing more, for tiny seizures like you mention. I have had two seizures (both for a cold medicine that had a small amount of codiene) and I passed what I will only describe as a SIGNIFICANT federal background check only three years after the last siezure.