Mushinski was optioned to Triple-A Sugar Land on Sunday.
The left-hander was called up from Sugar Land on July 23 and made four appearances during this two-week stint in the majors, allowing one run on four hits with five strikeouts and a walk over 5.1 innings. Mushinski has pitched to a 2.79 ERA in eight outings overall for Houston this season, so he'll likely receive another chance in the big-league bullpen down the stretch.