Hi, I’ve had similar times (3-4 weeks) with my PC boards ordered from Seeedstudio delivered to USA. At this point I generally expect about a week in production, a week in customs (either in Hong Kong or here somewhere in the USA and a bit less than a week in transit. I’ve ordered several batches of boards with no problems - I once received boards with the silkscreen layer messed up due to a change in the Seeed CAM spec that I hadn’t noticed and they replaced my boards at no cost (which was very unexpected - nice!). I am very satisfied customer of Seeedstudio. I’ve ordered from them since 2008 and only that one time ever had any sort of problem!
-Galen (http://www.droidbuilder.com).