No problem'o mate. The glitch/problem was bugging me every time I saw your avatar. 
Here's a cleaned version without the leftover crud in the last half of the animation.
I don't know it, but there should be a setting to choose between those behaviors: adding frames on top of each other (who would want that and what for?) vs replacing frames with the next one. The latter is what you want. There might also be a useful preview-in-browser feature.
Oh, Jasc Animation Shop, and this is a software glitch, i didnt see it 
The black trail is possibly a software setting / glitch. What do you use for anims?
I with Assyrius. It is a great style and looks good, but it would look better without the black trail.
Nice avatar! The black trail on the upward movement on the wings kinda bugs me though. Other than that, strong and simple character.
simply adorable