Ran out of Oxygen
 

I normally aerate with pure Oxygen and I ran out and didn't realize it.
When I transfer my wort from the kettle to the fermenter I just let it drain straight in from a fall of about 2ft and it creates a lot of agitation.
I also shook it for a couple of minutes. Will this introduce enough Oxygen to ferment well?

Well it's not as ideal as using pure O2 but it will work...Something similar happened to my last brew. The airstone blew off the tubing and into the carboy. I just shook it really well and called it good. I still had a vigorous fermentation and hit my FG.

Until very recently, the concept of using oxygen to prime wort was unheard of. Somehow, for the last few millennia, beer has been made. You will be just fine, I promise.

Why would you think that you don't have enough oxygen introduced after a free fall and shaking?

I dunno.
I'm just being paranoid, but my brew day went perfect up until that point.
I brewed a Two Hearted clone and want it to come out spot on, and I'd be very disappointed if it doesn't.

Update
 

Checked the fermentor.
12 hours after pitching 2 quart starter harvested from from Bell's Pale Ale, and I already have over an inch of krausen!
I'm definitely gonna need a blow off tube.
So far I'm battin a 100!

According to Jamil and chris white's book yeast, optimal oxygen levels is 8-10 ppm. the book also did an experiment of shaking a carboy of wort for 5 minutes and determined that the oxygen level was 2.71.

Also, here is a post from wYeast Labs that describes oxygen levels of wort:
http://www.brew-monkey.com/brewschool/oxygenation.php