"It's been kind of lingering a little while," Pederson said Friday. "It's hard for me to even put a finger on when it happened or how it happened."
Jeffery, who is listed as questionable for the divisional matchup against the Cowboys, was a limited participant during Thursday's practice after his ankle did not fully heal over the Eagles' bye week.
Jeffery was listed as a full practice participant on Friday.
The 27-year-old Jeffery, who told reporters that he expects to play against Dallas, has appeared in all nine games so far this season and has 34 catches for 500 yards with five touchdowns. He is coming off arguably his best game of the year, catching six passes for 84 yards and a pair of touchdowns in a win over the Denver Broncos.
Elsewhere on the injury front, tight end Zach Ertz (hamstring) and cornerback Ronald Darby, (dislocated ankle) have been full participants this week. Ertz missed the Denver game, and Darby is expected to make his first appearance since the opener vs. the Washington Redskins.