I'm assuming, since it all you posted about, they are the only things you have noticed that have changed.
Because they are so inflated by water, they are the first to show signs of any stress. Have you checked for anything odd like metals or heater malfuction? Anything that could be different from the water change yesterday?
I think that a heater malfunction would cause a reaction from my ground probes and/or GFCI circuits...
As for water, did the usual post-water change tests:
ALK - 11.2
CA - 410
MG - 1380
SG - 35ppt
ORP - 380
pH - 8.29
Plus a couple extras:
PO4 - <.20
IO - .03
LL :crazy1: