Lemons and Bricks have a "brick" nose, that is, a pink nose (and green eyes!)..
However, they are born with their pink nose.
All other beagles have a black nose, some darker than others.
3 things can make their nose pinkish:
1- an inheritate depigmentation. It usually affects the nose and the lips. Typically, the depigmentation occurs slowly anywhere after 2 years of age and never passed 4. It is believed to be linked to an innate vitamine B deficiency. However, vitamin supplement does not seem to help once the depigmentation is noticed. Certain insist that it is because it should have been given BEFORE the depigmentation occurs.
2- a fungus. There are certain form of fungus which makes the nose appear, greyish or pinkish. Given your description of greyish, you may want to check with your vet. This form of fungus can also affect the underpads. It is easily treated with a medicated cream, or with...Crest toothpast (yep, no kidding!)
3- Plastic bowls. Some types of plastic creates a chemical reaction and caused discoloration of the nose and mouth. If rectified quikely, the dog may recover his colour.