Was on mobileadmonitor just now, spotted some 320x50s I made a few weeks ago from scratch.
After the initial wtf subsided... I'm flattered!
Get used to it is the only advice i can give you.
Depending on the niche (but especially on adult), as soon as you're #1 bidder on big placements, you can consider yourself lucky if you haven't got ripped within 24-48h from launching ^^
best to take it as a compliment.. banners are "Shared" quite often in this industry...obviously there feeling your style... keep up the good work...and send me some high converting creatives...lol
Yeah you are right to be flattered. While nobody specifically picked up your banner, you are at least running enough traffic to get picked up by the spy tools.
Last year I made my own angle+banners and ran for months until the offer stopped (app install), and was shocked that nobody stole my banners/angle. You might even say I was a little offended (jk)
I saw advertiser using my lander as a offer page