Do you notice it when you are using your ipad normally? If not, you're fine. If you see it when doing normal stuff then exchange it.
I personally don't go looking for issue. If I see it in normal operation I'll ask for an exchange, but I won't go looking for them.
Why not look for problems/issues? not like we getting these for free or at a discount.
and it's not like they all have bleed, some do and some dont.