This will be your muscles saying;
" please give us a light ride. Work us gently. You thrashed us then did 3 endurance rides... we needed a recovery ride after this four day workout to disperse the lactate properly...
"... and now, well, you asked us to step up our strength by the demands last week, and we have, and we are ready so take us on a bike and spin us round... you'll be surprised, if you give us a light workout yoday, how much power we will have tomorrow...."
Remember, BabyBlue that recovery rides are an important part of getting fitter.
The general malaise was probably general tiredness if this is not what you usually do in four days... plus it coincided with yucky weather.
BTW... am envious of your power tap...