I felt a little flat and more winded than expected

Saturday, 9/26-Met with with Chuck and Chuck at Westtown for a workout.  Chuck S. and I did the workout he proposed, 3x1000 and 3x500.  His target pace was 3:35 for the 1000s and 1:35 for the 500s.  There was equal rest period (i.e., the time of the run).  Chuck K. ran 3x800, 3x400, and a couple of 150s.  We ran behind Chuck on the 1000s.  Maintaining a good distance in front of us on his 800s (our 1000s), he ran about 2:33, 2:29, and 2:34.

My runs:
1000 #1: 37/80/2:03/2:45/3:26
1000 #2: 38/80/2:03/2:44/3:25
1000 #3: 38/79/2:01/2:41/3:21
500 #1: 36/73/1:32
500 #2: 36/74/1:32
500 #3: 36/72/1:30

Although I managed this workout okay, I felt a little flat and more winded than expected.

Chuck stayed within 2-4 seconds of me on each repeat.

Friday, 9/25-took off