Near Washington DC?

I work north of Washington DC, and a few months ago I spotted off in the distance an object in the sky...it was a sunny clear day.......it seem to have curved up ends on either side and kinda diamond shape(from my angle it looked diamond shaped)....it was moveing very slow and rocking left to right as it was moveing away towards Andrews AFB.....everytime when it rocked to the right the sun reflected off of it very bright, and when it rocked to the left it was almost invisable except there was a dark underside to it....I thought maybe a jet but it was to slow and too big and it was rocking back and forth too fast. I was wondering if anyone had any idea what this could have been?

C'mon gang! Lets investigate!

Sorry, couldnt resist.

What could you not resist?

He was making a scooby doo reference

That sounds creepy, some sort of x-plane?

XAOS