No, it's not unusual. Many even get a few starts in MLB in garbage time before they get converted. It's too early to say where Romero ends up given his injuries. They've put him on a weird track even this year - skipped Wilmington, now getting roughly a month in AAA.
well, he was in camp last year and pitched some in the majors, so I don't think he's considered an A ball pitcher. I'll guess Fredericksburg was more rehab than anything.