I felt it in my office while Transformers: Dark of the Moon was playing to 48 people. I didn't think anything of it as I'm use to the blasting in the Cement Company quarry on the edge of town which shakes my theatre more then that did.
I wouldn't have even known that it was an earthquake if it hadn't been for a woman who came to the lobby to answer her cell phone. It was a call from her son in Washington DC to tell her that they were all right. She then told me.
None of the other patrons were aware that it even happened. I guess the noise of the explosions etc. in Transformers hid the rumblings of the quake. And if they felt anything they probably thought that it was just from the sound system sub-woofers. They tend to shake the wooden floor a bit too.
The proprietor of the Coffee shop next door said that everything on his walls shook, but I hadn't noticed that in my office.
There was a reported aftershock at around 8 PM during my evening show, but I didn't feel anything that time.
For those not aware of it, I'm located about 60 miles north of Philadelphia.