Allen does not believe the injury to be serious, the source said.
He finished Sunday's 27-20 loss against the Green Bay Packers with 14 receptions for 157 yards but missed the entire fourth quarter with the hip injury. He had 11 catches for 128 yards in the first half alone.
Allen said Sunday his hip "kept pulling me," according to the San Diego Union-Tribune. "I couldn't really run like I wanted to."
Allen was Philip Rivers' favorite target Sunday, as the quarterback set franchise marks with career highs of 43 completions, 65 attempts and 503 yards passing. He also threw for two touchdowns for the Chargers (2-4). His 43 completions were the most in NFL history in a loss.
The Associated Press contributed to this report.