Thomas sat out Sunday's session of rookie camp with a sore groin, Bob Condotta of The Seattle Times reports.
Thomas is the only veteran currently on the Seahawks' 90-man roster participating in the camp, but he took Sunday off as a precaution to rest the injury. He likely will be back as a full participant sometime this week as he continues to seek a spot on the final roster.
The Seahawks waived Thomas on Friday, Aaron Wilson of the Houston Chronicle reports.
Thomas was picked up off waivers from the Browns on Monday. It's unclear who the Seahawks added to fill the roster vacancy.