OK, so they shot a smaller, faster moving target. The original point still stands.
It was an F-117. Yes, most "F" aircraft are air-to-air fighter aircraft. However F-117 is mostly used to attack ground targets, so it's "F" should be more like an "A" (If you want to nitpick that is ;-) )
Though no-one knows for sure, it's also been rumored that the fighter designation was done as a security measure to hide the true purpose of the aircraft, or that the F-117 designation existed in early planning documents and was simply never changed once the aircraft became a reality.
It's also not the first attack aircraft to carry a fighter designation; the F-111 long-range attack aircraft also carried that designation (though in that case it was because the aircraft was originally meant, in part, to fill an Naval air-defense fighter role).
Actually, they are both subsonic aircraft and have a very similar top speed. The F117, however, has a larger radar cross signature, which makes it appear as a larger aircraft than the B2 in a radar return.
It's been a decade since I read much about it, but this site states that the F-117 has a radar cross section of 30 square centimeters while the B-2 has an RCS of 14 square centimeters.
