CAS_* files? | Peter's Custom Anti-Spam for WordPress | Forum

What are these files? More importantly, can I delete them? Even more importantly, can I prevent them from proliferating!?
They are not included in your release, and seem to be generated.
I have over a hundred of them:
cas_AWhVda
cas_bMXTWP
cas_BYeeYV
etc…

They all reside here:
wp-contentpluginspeters-custom-anti-spam-image

Thanks! That's what I thought.
Are they automatically generated every time? Or only when a user requests the audio?

And on a sidenote, I've had a couple of bots get through lately, prompting me to update the plugin (only 1 rev behind) and throw a few more fonts/words into the mix.

Thanks for a great plugin, and keep up the great work!