A Rockies trainer confirmed Wednesday to the Denver Post's Troy Renck that Huston Street (shoulder) has indeed experienced a setback.
Street halted his throwing program this week and wouldn't say why when asked about the issue on Wednesday afternoon. He's still aiming to return some time in May, but the Rockies can't exactly form a timetable. Franklin Morales is expected to fill in at closer for the Rox until Street returns.
Source: Troy Renck on Twitter