They replace your card if there's a chance that it has been compromised, not just if they know it has. Like they may have had a security breach and lost a thousand credit card records, and yours just happened to be one of those leaked.

By the way, I would take that guy seriously when he says "not yet". There are some truly scary technologies being developed in the name of security. A good question to ask when people talk about security is, what's being secured; and another is, what does it actually cost. Not in money but in freedoms.

I try not to be too paranoid, but... They're not out to get you, but if they were, you're screwed.