For three days now i have been feeling a constant, deep, and mild warmth in my arms, as if blood were rushing in (though without the actual rushing sensation). should i be concerned?

No not from your description.

I agree that your symptom isn't worrisome. The brain communicates with the skin. This could be caused by tension or stress. Could this pertain to you? If so calm& relaxation are in order. If chronic anxiety or stress is a problem & symptoms are common, stress management therapy by a mental health professional would be beneficial.