Ok I figured out the second part, it's not a time range. The second portion is the time offset from UTC time.
So, when I look closer:
For an older form (from last week) where the time is displaying correctly, the offset is of 6 hours
<my:FinishTime>16:00:00-06:00</my:FinishTime>
<my:StartTime>08:00:00-06:00</my:StartTime>
For a new form (from today) where the time is wrong, the offset is 7 hours.
<my:FinishTime>15:00:00-07:00</my:FinishTime>
<my:StartTime>09:00:00-07:00</my:StartTime>
This all seems logical, or am I just tired?
First off, why is SP displaying the time WITH the offset in the SP List Column? Eg: "09:00:00-07:00"