Aggregation using Simple Aggregation persists after disabling the module

I have disabled this module while I make some CSS changes, but the files it creates seem to persist. I clear the cache and the combined files go away until I refresh the page, but then I see the following again, which I believe come from this module. Here's one:

<link rel="stylesheet" href="http://foo.com/modules,_system,_system.base.css,qn0wclb+modules,_system,_system.messages.css,qn0wclb+modules,_system,_system.theme.css,qn0wclb+misc,_ui,_jquery.ui.core.css,qn0wclb+misc,_ui,_jquery.ui.theme.css,qn0wclb+modules,_overlay,_overlay-parent.css,qn0wclb+modules,_contextual,_contextual.css,qn0wclb.pagespeed.cc.QOwbGZWvN_.css">

If this appears to be from something else, please let me know. Thanks in advance for your help on this!

UPDATE: I think what I was seeing comes from ModPagespeed - my apologies!