Digital BW, The Print

I have stored a supply of XP2 well past it's due date in my freezer. 
Are there any obvious signs of deterioration negatives from outdated
film?  The last two rolls show some "mottling" in the shadows.  It is
not posterization, but rather a coarseness and some lack of detail. 
Midtones and highlights seem fine.  Is it time to toss the film?  I am
relatively sure the problem is not a function of scanning or
processing in PS.

Thanks for any help.

Steve