my experience in the past has been i enter the tracking # and the usps site shows only the date it was registered in china, but never any tracking info. then the package arrives at my post office and still the tracking record is empty. however, as i have a package en route i checked as i read your post and for the first time i see current info. it took 11 days to go from shanghai to nyc. as of april 28th, that's where it states my package is - even though today is the 30th.
i hope the time frame of my package's shipping is is helpful for you to get a sense of your shipment. and one tracking record kept up to date and none others may be an anomaly, so i wouldn't worry
- i know you wrote you're not worried so like all of us anxiously waiting for a package - i should have said, don't worry about the lack of info on usps web tracking.