Do you see this in live or only on the photo? There was a thread recently where it was shown how photos taken with cellphone cameras can create apparent bleeding or brightness fluctuations...
In any case, based on the photo, I think it is acceptable. I would check if it bothers you during normal use, e.g. watching a dark-ish movie in a dimly lit room, playing a game with mostly dark backgrounds, or something similar. If the bright corners are notable there you could consider having it fixed.