I guess we all want to believe that LE knew what they were doing all along. I just can't subscribe to the thought that they stopped him not once, but twice in the same day for an offense that (please correct me if I'm wrong) usually does not result in a ticket. I feel that it had to be intentional. Whether the intent was to spook him, let him know he was being watched in some capacity, confirm the Elantra was actually his, whatever the reasoning, I think it was purposeful.
A theory that makes total sense to me would be that they initially pulled him over to see if this was in fact the Elantra they had been looking for- remember at that time the entire country was looking for a white Elantra. Again, MOO, but I bet they pulled him over, confirmed it was in fact him, and made an additional stop shortly after to gather more information. Perhaps the first officer noticed something that needed a second look, maybe they were trying to gage his reaction, who knows. I for one have never been pulled over twice in one day, however, I feel like if I was and told the secondary officer I had just been pulled over for the same exact infraction, I would be issued a ticket or at least an on-the-record warning.
JMO