Hi Buddydootybusy:
How are your Squirrels doing? What is the status of the "bumps?" Are they still present and have there been any changes? Were the bumps simply small, firm bumps on the skin or were they actually blisters (blisters or vesicles are fluid filled pockets in the skin that are covered by the thin surface layer of the skin?
These bumps appear to me to be Milia. Milia have a number recognized variants but they are probably most commonly found in mammalian babies; both animal and human. Milia are small bumps on the skin that may be firm or partially fluid filled that result when immature skin begins shedding normally occurring dead skin cells and those cells and associated cellular materials become inadvertently incorporated within new but immature skin. Mila that are associated with immaturity (babies) usually resolves completely and without intervention!
I have pasted a representative photo of Milia from Blackwell's Five-Minute Veterinary Consult, Clinical Dermatology 3rd Edition 2018 which is a "quick" dermatology reference I often use:
Just to be clear, I cannot be certain that the "bumps" seen on your Squirrel are Milia but they have the appearance of this and because of this, I did want to make this known! If these bumps are still present, please post a recent photo if there have been any significant changes. A visit with a Veterinarian is often beneficial in making diagnoses but this, unfortunately, is often an impossibility when the patient is a Squirrel!
Regards,
SamtheSquirrel