The 19-year-old picked up a knee complaint against Luton Town on Saturday, which limited him to just 12 minutes on the pitch before he was substituted.
"It's a crying shame. I just think he lost his footing. It was innocuous," manager John Sheridan told the Plymouth Herald.
"I'm not sure of the extent of the injury. We will have to wait and see. I'm hoping everything is okay."
Bray only arrived at Home Park last week.