It looks like the website that Spinnerette uses got an overhaul and Dosage needs to be updated to support it.
cwbetts@CW-M3-MacBook ~ % dosage -a --adult Spinnerette
Spinnerette> Retrieving all strips
Spinnerette> ERROR: XPath //img[@id="cc-comic"] not found at URL http://www.spinnyverse.com.
Spinnerette> WARNING: XPath //a[@rel="prev"] not found at URL http://www.spinnyverse.com. Assuming no previous
comic strips exist.
It looks like the website that Spinnerette uses got an overhaul and Dosage needs to be updated to support it.