With two MA's combining to a 3.7, it might raise questions on how you were unable to bring it to a 4.0, as many aspiring doctoral students gun for a 4.0 in an M.A. program to make them as competitive as possible for the top PhD programs. This cycle has been especially competitive, so I think that you receiving an offer from any school is spectacular news (especially since you only applied to four programs, and many people have cast a wide net with 20+ applications).
As far as low undergrad GPAs go, from what I have seen and read, excellent performance in your graduate work should realistically make up for it.
I would consider it to be worth trying to "aim higher" in future cycles if you are concerned that everything you'll do during your PhD + the prestige of the program will seriously hinder you from finding any sort of academic work. However, I'm sure you are already aware of how competitive seats at top programs are, as well as the steep competition for any faculty position that opens up.