Alonso underwent surgery on his left knee last year after an ACL injury, which forced him to miss the entire 2014 season.
Coach Chip Kelly told reporters on Saturday that Alonso's tendinitis, which has prevented him from playing this preseason, was not connected to his surgery, but Alonso himself said the two were related on Tuesday.
Kelly said the condition was not very pressing, and that Alonso would practice this week before being reevaluated.
Alonso, 25, was a second-round pick by the Buffalo Bills out of Oregon. He had 87 tackles, four interceptions, two sacks and two fumble recoveries for the Bills in 2013.
The Bills traded Alonso to the Eagles in exchange for LeSean McCoy in March.
- Kayla Lombardo