The OU tried to put a DE (dairy equipment) at a certain time. It didn’t work, so they will put an OUD even if it is not milchig but made on equipment that was used for dairy. I don’t know if the equipment is “kashered/sterilized” to avoid this problem, but I’m not into giving hashgochos so…
I would be careful about just looking at the ingredients. You cannot rely on allergy warnings because that is to avoid lawsuits. So if the equipment was ever used for milk/nuts/etc. they put the warning (even if there is none in the product being used.
FYI–the OU started with Educator cookies which were also not “pas Yisroel” but they tasted good. 🙂