I didn't get the sense that Katie was trying to signal the LEO. I got the impression that they had all slept in the car the night before, Baby was crabby in the backseat, toddler was restless and wanted to stretch out after being in the car all night but the drizzle was keeping her stuck in a messy car full of flotsam from a long road trip. I think Katie and all had probably spent an uncomfortable night in the car and not gotten much sleep.
Aviles on the other hand was a bit sketch IMO, asking why the cop was asking them questions, if someone had reported or complained about them being there, etc.
Katie (to me) did not appear nervous, however Aviles did. JMO