Yes that is odd. Why wouldn't you notice the same amount of difference either way? Tires get hard and lose grip over time even just sitting around but I wouldn't expect most guys to notice the tires they mount come spring don't stick like they did last summer.
With audio my experience is once you get used to really good sound going back doesn't sound worse, it sounds broken. That was my reaction, literally, first time I tried a good interconnect. After listening a few minutes to the dealers XLO interconnect I put my freebie patch cord in. Instantly, abject horror! Dead certain I had somehow broken this guys amp! But no, it was just the crap patch cord. Which until then I actually thought sounded pretty good.
Same thing happened again more recently. Really good interconnect, only stone cold, which I then somehow hooked up going the wrong way, which together with a few other things (long story) made my system sound not just worse, but broken.
But seriously, you don't notice your summers grip and respond a whole lot better than your winter's? Really??? What're you running???