@Tucson - It doesn't seem that unusual. You had a good stretch of conditioning and then pushed yourself a little harder/faster. I think conditioning only gets you mostly ready to step it up a notch but more effort will be more tiring at first even if you are ready for it and even if it doesn't feel like it will be while you're expending the effort.

Because my Wednesday night paddle didn't happen last week, I went from the previous Saturday morning until late Sunday afternoon, about 8.5 days, without paddling and the 8.7 miles I paddled yesterday has me feeling more beat the morning after than usual. There is something to be said for the right amount of rest/recovery. Not too little and not too much.