Yes it is duty time for any 135 flying that follows.
The reg states that you must have had 10 hours uninterrupted rest within any 24 hours in which 135 flight are performed. But your day can be legally longer than that look-back 14 hours if further Part 91 or travel is required. Those are not inclused in the duty time limits. Your next Part 135 day's duty will start later so that tbe required 10 hours of rest can occur.