Board Thread:Show-Related Questions and Answers/@comment-5344051-20160229080952/@comment-25536775-20170430185030

DSP88 wrote: Regina stated that she brought who she wanted so that leads us to believe that she was able to choose who came along with the curse and who was left behind in the Enchanted Forest and elsewhere. So areas like Camelot most likely weren't even on Regina's mind so they stayed frozen for 28 years.

That's most likely what happened.