Brakes are where it needs to be, seat post has dropped about 2cm. Tire pressure dropped to about 90psi.
In terms of cadence, I try to keep it around 90~99, where I feel the most comfort. Usually don't go into <85 unless on the climb for brief periods.

It has been getting quite windier and more humid lately. I guess I really never took that into consideration along with resting.
Rule #5 needs to apply as well (and number #10 perhaps?) . Riding solo doesn't do the trick as well as riding with someone else better I guess. There just doesn't seem to be too many group rides in Chicago which is surprising given the number of bikes and bikers in this city!
It looks like it's a combination of whole bunch of things. I will take a rest for a couple of days, rest, eat well, harden up and see how it goes
Thanks for all the pointers! really appreciate it!