I agree with the others here - you were never arrested, charged or convicted so there should be no paper trail. This would be similar to being pulled over for speeding and given a warning. Are you going to tell your future employer how many warnings you received?

And no, Rick, I've never heard of airlines asking about customs stuff and I most certainly do not believe they have any access to internal data. Since background checks are typically farmed out it's anybody's guess as to who is privy to that information - but honestly, I don't think it's even worth a second thought.