Daenerys did indeed follow after Jorah with Missandei in tow. She hung back a bit so that her dragons would not be swayed by her presence. No, this was meant to be a test for Jorah.

Still, Daenerys watched anxiously as he approached Rhaegal. When Rhaegal approached in turn, Daenerys couldn't breathe. But she worried for nothing, it seemed, as the dragon allowed Jorah close. Vaguely Daenerys could hear Jorah speaking Valyrian to her dragon and her heart soared. When Jorah climbed atop Rhaegal's back, Daenerys wasted no second longer to approach Drogon, who eagerly allowed her onto his back.

"Congratulations Ser Jorah," she reached out to him. "Or should I say 'husband'?" She grinned.