Houck was returned from his minor-league rehab assignment Saturday due to a recurrence of a right pronator strain, Ian Browne of MLB.com reports.
Houck was first diagnosed with a right pronator strain in mid-May, and he subsequently landed on the 15-day injured list. The right-hander kicked off a minor-league rehab stint about a month later and pitched in five games, posting a 5.74 ERA, 1.53 WHIP and 15:6 K:BB over 15.2 innings between Double-A Portland and Triple-A Worcester. There had been optimism that Houck was close to being activated, but the setback means he'll likely be out for another significant chunk of time.