Pearl's so startled she falls back onto her butt and sits there looking horrified, the spell only broken when Steven bolts away from her. Yelling at her would be one thing, but those vines- there was something so ominous about that. Steven's never attacked her before.

"Steven!" she yells and reaches after him, distraught. She's up on her feet in a moment and breaks off in the same direction he just ran in, looking around frantically. "Steven you come back here this instant!"

If she sounds angry, it's mostly out of fear, because she's pretty much completely terrified.