Well that would be a sign. And in case you were wondering, a reader writes:

That free newspaper they give out [in NYC], Metro, has a front page story on what the NYPD has said to watch out for in regard to terrorism. Honest to God, one of the “warning signs” is a guy running around with wires coming out of his jacet or back pack.

UPDATE: Many readers point out this could also be, say, an IPOD.