Alright, I'm not sure about the wet tissue reed question, though I think that might be describing warped reeds, like they weren't held flat during their humidity adjustments.
As far as the freeblowing topic, I am pretty confident I can further the discussion there because I've dealt with the same exact issues previously. A lack of that freeblowing feeling is often the result of embouchure interference, or, in other words, too much embouchure pressure distorting the reeds shape and making it more resistant. This is exactly whats happening after a short layoff. You start out with a nice loose embouchure and after some playing your embouchure begins tightening to control intonation as your vocal tract and abdominal forced exhalation muscles begin to tire. So, basically the embouchure tries to pick up the slack of what your vocal tract and air support should be doing. Like I said before the embouchure pressure distorts the shape of the reed, often pushing the corners of the reed up and in, making the reed more resistant and also affects the tone taking away from purity and clarity. So, instead of just going at it after some time away, do a nice warm up of long notes, take a break, and come back. That should help you play longer and help your abdominals and vocal tract continue doing their fair share of the work load.
As far as the relaxed state of mind goes, I do have a guess there as well. Mental tension (or fatigue) can result in muscles not responding at their prime. Again you could be suffering from similar fatigues as mentioned above or you might just be playing with more embouchure pressure from the get go. Mental tension can also equal physical tension.