Or - she could have a respiratory infection that will only go away with oral benadryl or other antibiotic that will need to be prescribed by a veterinarian. I'd go ahead and plan to get her seen. Unfortunately, pet store feeder rats aren't kept in the best of care.
If you plan to keep her as a pet, please do get her seen - because you're going to need to get her a buddy rat as well, and you need to make sure they're both healthy. Rats do much better in pairs (two girls or two boys).
Most all of my rats are creamed hoodies (as well as being dumbo's).