The seven-time Pro Bowler said he wouldn't attend OTAs or minicamp two weeks ago at a charity function. Johnson, who'll be 33 at the start of the season, said he wasn't sure if the Texans were a good fit for him anymore, but did not elaborate further.
OTAs are voluntary under the league's collective bargaining agreement.
"I have a ton of respect for him," first-year head coach Bill O'Brien said Tuesday, adding that he and Johnson have had positive conversations. "We'd love to have him here now. That's up to him."
Johnson reportedly hasn't formally requested a trade or spoken to team management about his contract.
Johnson remains productive, as last season was his fifth with at least 1,200 receiving yards in the last six years. He finished with 109 receptions for 1,407 yards and five touchdowns.
But O'Brien will be his third different head coach as he enters his 12th season with the Texans. In that span, Houston has had only three winning seasons and two playoff berths. SI WIRE: Louisiana legislator pulls NFLPA-opposed workers' comp bill