Have noticed this every now and then occur, but noticed I only had 33 plays offensively and 22 plays defensively before my first pre-season game in 75. I didn't touch my playbook at all in the off season, but didn't think it was a big deal. After my 2nd pre-season game, my playbook was back to 33/22 after I selected 40/30 the day before.
Noticed this bug happen every now and then, but starting to concern me a little, especially right before the regular season begins.