Jason Peters was absent as the Eagles opened their third week of organized team activities on Tuesday.
OTAs are voluntary, but coach Chip Kelly has mostly had full attendance during the first two weeks of workouts. Peters, along with several other Eagles, missed last Monday's practice because of travel delays.
The Eagles had no explanation for Tuesday's absence, though.
"He's just not here," a team spokesman said.
Peters is returning from a ruptured Achilles tendon that caused him to miss all of last season. He has participated in all facets of practicing this spring, and Eagles offensive line coach Jeff Stoutland told reporters last week that it didn't look like Peters had even missed a beat.
Peters, 31, was considered by many to be the best left tackle in the game in 2011. He was voted into his fifth straight Pro Bowl that season. The Eagles line was best by injury last season. Center Jason Kelce (knee) and tackle Todd Herremans (foot) suffered season-ending injuries.
Evan Mathis had what the Eagles called minor ankle surgery earlier this month. He has missed practice since then but was out working with the rest of his position group at the start of Tuesday's practice. He isn't expected to be 100 percent until training camp.