Flaherty, who's scheduled to pitch Sunday against the Reds, could see his next start pushed back a day, Jenifer Langosch of MLB.com reports.
Manager Mike Shildt conceded Thursday that he's considering building in an extra day of rest for the young right-hander. Luke Weaver or Tyson Ross would be the leading bullpen candidates to make a spot start Sunday if those plans came to pass. More definitive word on the Cardinals' weekend rotation plans should emerge at some point Friday.