Yanwen tracking

This is off topic, so I’ll ask it here. Placed my first order with Heltec, which shipped from China to US on 3/28, via Yanwen. I have a Yanwen tracking no. and another for USPS as “last mile”. The Yanwen tracking was quite active until 4/1 when it reported “release Import” and “picked up by local carrier”. OK, that’s good but USPS s silent. USPS shows the tracking no. being assigned on the 28th but no other action. The parcel has gone off the radar for over 72 hours. At what point should I become concerned?