I replied to jayman11's post in the other thread, but I'll post here too so more people see it. I just fixed this issue on my site. It seems that the USPS is now returning the method ID's in all uppercase and it's using a case sensitive match that's causing it to think you haven't chosen a shipping method. It then chooses the first available method, which happens to be Express. All you need to do to fix it is edit usps.php and update the keys in the $this-types array to be uppercase.
Edit: tarheit, I don't use days in transit myself, so I can't say for sure, but I'd bet this fixes that too.