$sel->set_browser_log_level('error');

It must be called after a page has been opened. I'm still curious why, without explicitly setting this, you get different "log level" behaviors. No matter, my question is answered!

UPDATE:

I was barking up the wrong tree entirely, and my solution is a Perl solution :) The 'set_browser_log_level' method is not the one I wanted, it only concerns the UI and I run mostly on the command line or some flavor of a console. No no, the selenium webdriver, the .jar file you must launch to run a selenium test is my culprit.
I was starting the webdriver with a system call in my code. This would show output from the webdriver right along with the output from my test code. By spawning a secondary process under a separate (possibly hidden) console, I can keep the output I want and divert the "INFO" stuff from the selenium webdriver to a secondary place (or ideally, I'll just find a way to suppress it altogether.. any help there would still be appreciated!)