If I filed electronically 72 hours ago and still pending should I be concerned?

It is not unusual for your return to stay in pending status for several days sometimes longer depending on the back log of returns filed and time it takes for the IRS to process them. Keep checking the IRS Where’s My Refund? site for updates. The tool is updated daily (usually in the overnight hours) so you don’t need to check more often. Please see the TurboTax FAQ What does "Pending" mean? for additional information. 

You can check that your return was received by the taxing authority  using these instructions: Check the Electronic Postmark of your Return. Pay close attention to the separate lines for Federal and State. They are separate statuses.

Once your return is filed, TurboTax has no control over the processing of your return or the release of your refund.

Here are a couple FAQs to track your refund:
When will I get my federal tax refund?
How do I track my state refund?
Why does Where's My Refund say "approved" but TurboTax still says "accepted"?