My parents traveled to the USA a couple of weeks ago (Caracas - Miami). It wasn't their first time; they've probably come and gone a dozen times by now, and they've never had a single issue. This time, the immigration guy was kind of pompous and, once they told him they weren't staying at a hotel but with some friends, he began looking at them somewhat funny. Finally, he stamped their passports (normally, with entry date and a 6-month term of stay) but he put an additional stamp, one that no one they asked had seen before:
It seems to be the same usual entry stamp, but cut in half. What does it mean? Should we be concerned?