Hey David -
I don't have first-hand experience with what you've run into, but I found another customer who ran into the same thing:
Their commands complete despite this message - did your PNG get created?
From what I can see, this message is just a nuisance, and doesn't really amount to anything. The message itself was associated with a related bug which we fixed in Server 6.0.2, but the "nuisance message" still appears to be hanging around.
Let me know?
Thanks for the update - you're right...these are just warning messages. I thought the last 406 error was a result of those SSL warnings but it turns out this was an authorization issue with the account I was using.