Is this a run-on sentence?
After playing an hour-long set for nearly one hundred cheering fans, Hunter's band returned to the stage and delivered a stellar encore performance.
A: no
B: yes
This is not a run-on sentence. It is not formed from two sentences that have been run together without appropriate punctuation.
After playing an hour-long set for nearly one hundred cheering fans, Hunter's band returned to the stage and delivered a stellar encore performance.