StubHub's website does not update the shipping status as quick as UPS. If UPS shows the package has been shipped and en route then you can go by that. As long as you have shipped the tickets in time, you will be paid regardless or not if the tickets get delivered in time. You don't need to do anything else.
StubHub will update the status automatically. They seemingly do not sync in real-time with UPS and as such, it sometimes takes a day or two (more if it was a weekend like in your case) for the system to update.
I've had the system not update as shipped until that tickets were actually delivered and I had the same concern. That scenario has happend several times to me but I have never not been paid or had any delay.
Hope that helps