Passport still hasn't been delivered

Is there anything I can do about trying to track down my US passport? I sent it from Canada to the US for renewal a few days before the strike. Tracking says it went through customs on Dec 21 and was "processed Philidelphia" later that day, and since then has just been "In transit." I'm assuming it's in the hands of USPS at this point, but shouldn't I still be getting notifications? Has my passport been lost? Is this because of the strike, or is all on the US side now?