My released squirrel is pregnant, just noticed nipples two weeks ago.

Yesterday, I watched her lick tar in the middle of the road (a small side street) for 5 minutes. I kept watch, and no cars came at all. When she finished, I went out to look at where she had been licking. It was one of those tar patches that they put down as patches to fix small issues in asphalt pavement.

I assume her body is telling her she needs a nutrient? Has anyone seen this, or knows what she is looking for that she licked tar for so long?