ADV7391 with 2.5V I/O

We are using the ADV7391BCPZ video encoder and want to confirm that 2.5V I/O voltage is stable with this chip. 

We have a rev-1 prototype that may have a flicker once in awhile in the composite video.  We see this on an LCD and not on an old fashioned CRT or on a scope terminated to 50 ohms.  Could the I/O voltage running at 2.5V be an issue.

For VDDIO it says: (Table 3 page 7)

     Min 1.71V

     Typical 3.3V

     Max 3.63V

Table 15 (page 20) shows VDD_io as “Input/Output Digital Power Supply (1.8 V or 3.3 V).” And digital input/output specifications are only listed for 1.8V and 3.3V modes. 

So I am concerned if we are OK to keep running the I/O voltage at 2.5 volts