What did I see?

This is a litle off topic, but maybe someone here knows what this was.
Several years ago (5 maybe) in February, I was stargazing with a
friend. He was looking through his Dob & I was laying on my back
scanning the zenith with binoculars when a black delta winged aircraft
of some sort came into view. It had no running lights, made no
detectable sound & was flying at a lowish altitude (maybe about the
size of the moon in 7X50's), so I got a fairly decent view. I followed
it for as long as I could on its northerly flight path. I told my
friend what I had seen & he had no idea. I live 40 miles North of
Tampa...... Blackbird maybe?