No need to feel sheepish about that target...that's good shooting no matter how you held the firearm.
If it was done with a revolver there probably wouldn't even be any discussion about grip.
Regards,
Greg
BTW, you can clean a field stripped gun well enough to remove the Frog Lube. I used that stuff once and my shotgun failed to cycle the first few shots during the next morning's hunt. Following a quick wipe down with a paper towel and some 10-30w oil from the dip stick, I again had a functioning shotgun.