[WayneS]

Yes, there can be a temperature-based difference.

There can also be a difference between the readings obtained from two different gages (gage tolerance).

These anomalies are one reason the NFL provides a range of acceptable pressures for the footballs.

I this case, based on the % disparity of the claimed readings, and assuming NFL teams do not typically use cheap plastic junk pressure gages, the under-inflation claimed would almost have to be either intentional, or the result of a defective pressure gage being used to take initial measurements.

[CAluvdubya]

That makes sense.