Why did the e-file date of submit change when i filed my federal tax return?

The transmission report may show EST because that is the location of the IRS main office.  But, the local time of your return is what controls the timeliness of your filing.  So, as long as it was filed timely in your local time zone, then your return is on time.

Thankyou DawnC for answering my question. Thankfully, I filed before midnight (local time), so I'm in the clear:)