I just stepped through my code and it looks like the date values are returned as follow:
var newDate = new Date().valueOf()
newDate = 1360353562367
var newDate = new Date(); (without the ,valueOf() )
newDate = Fri Feb 8 13:09:05 MST 2013
In my case, if I do not set the date to .valueOf() I get an exception or sometimes it just converts it to weird cases. However, I found that when use the .valueOf the date gets converted to the UTC format. Again, I am not sure if this is the best implementation but it seems to work on my system - I am able to insert a new feature with a date stamp.
Sometimes, I oticed that I needed to do a complete refresh and empty out all cache by selecting <ctrl> <F5> when I initially load the page; just to make sure that everything is all a new ... just a hunch though. I found that the world of web development really has a lot of external unknowns. Good luck!