Hi PerplexyGlass (great avatar name btw)
Can you please try and provide a couple of good, clear images so that the members here can see what you have concerns about.
I don't want to be alarmist, but a dark reddish brown cere is not normal for a male. However, depending on age, females can develop darker brown ceres, especially when they are in breeding condition. So, until we can have some images posted of your new feathered friend
it would be hard to know what your concerns may be.
As I have said, it is not normal for males to have a cere turn dark reddish brown. If, in fact, your budgie is a male, then I would advise giving him his first check up with an Avian Vet. Preventive care, understanding, and annual checkups are important. Either way, he will need an assessment.
Of course, you can always bring him back to the supplier (not something that I would do if he was in my care) if you feel unwilling to provide him with a AV assessment, but keep in mind, whoever is the supplier should have maintained proper care and have a working knowledge of avian health and budgie anatomy before selling budgies that may be ill or show signs of a tumour.
Please provide us with some pics if you can.