Something I've noticed recently while playing is that I'll actuate the aftertouch and go the full range of the aftertouch and then shortly afterwards I'll play a few notes, even very very lightly, and a little bit of aftertouch gets triggered, about .01 to .07, and then it stays there, the aftertouch doesn't go back down to 0 until I either push hard enough to trigger aftertouch again or play a few more notes.
I know that the Keylab 88's Fatar TP 100 L/R has two aftertouch strips, one for the white keys and one for the black keys and I just tested it and this same exact behavior happens with both the white keys and the black keys, so it's unlikely that both of my aftertouch strips are defective.
Also, I never noticed this issue before and there was a firmware update released only a few weeks ago and so with all that said, I suspect this sticky aftertouch behavior is a firmware related issue.
This is a real issue whenever I have a VSTi patch where aftertouch changes pitch because when the aftertouch sticks at a low value it causes the patch to essentially go out of tune.