Ramon Calderon, one such fan, captured and posted the surprise moment on Twitter.
"After continuously breaking down in tears, @kellyclarkson just announced she’s pregnant - congrats!" he wrote.
"That was not planned," Clarkson reportedly continued about making the announcement, according to the New York Daily News. "I just didn't want you to think I was crazy. Honestly, I'm just hormonal today. Nothing's wrong; I'm OK. I haven't vomited yet!"
The three-time Grammy winner, 33, and husband Brandon Blackstock welcomed their first child, daughter River Rose, in July of 2014.