Have a look at EPST (dial ##778, select edit mode, passcode 000000), then check the modem settings against this thread. I had a similar problem as you and doing this fixed it.
In other news, it feels to me like 4G got a hell of a lot better since the outage. Faster speeds, slightly less lag, and I now get a signal further into buildings where I was dropping to 3G before. Might just be coincidence, but the 4G here in Boston has gotten a lot better in the last few days.