Silver plate is usually not lacquered, so this comes down to a metallurgical problem:
There are three metals involved: zinc and copper in the brass, and the silver, plated to the surface of the brass. The brass has a particular content of zinc and copper, and this can vary from type to type of brass. This can lead to certain problems with the corroding of instruments, one such problem being "red rot", where the zinc of the brass is leached out slowly, leaving only the copper. This will appear as a browny red stain in your (unplated) parts of the instrument. In instruments, this usually happens from the inside, or where there is contact with chemicals (including saliva) and it happens over a long period of time. Red rot is irreversible, and is a common cause of leadpipes needing to be replaced.
I don't think this is "internal" red rot though.
It is more likely to be a problem in the manufacturing process of depositing the silver on top of the brass, which we know as plating. As this link shows, if plating is done in a high humidity environment, as found commonly in Chinese factories, a reaction can occur between the copper in the brass and the silver plate, causing the copper to oxidise, leaving small lumps or blisters underneath the silver plate. This will show as bubbles in the silver plate. Do not try to pop them, or smooth them out!
Again, this is irreversible, and there is nothing that can be done. My condolences.
As an aside, this blistering can be seen in other areas of cheap metalwork - I bought a steel toolbox manufactured in China, it was powdercoated with a red "paint" cover. The process is somewhat similar to plating, in that both use an electric charge to help deposit the material onto the surface of the product. After just a year, blisters appeared in the red paint, which eventually flaked off leaving the bare (and slightly rusted) steel underneath.
Yes I have learned trying to smooth them out is not a good idea. Do you think they will grow? The size hey currently are is too small to see unless looking up close.