Seems like a big change to me! Helmutii always make me anxious, I think I had one back in high school and they seem to grow taller than other lithops - I was forever worried I was doing something wrong to it. They still make me anxious - so I don't have any (for now). How big is your collection Rika? One of my favorite posts is the one where you showed a picture of a bunch of your collection all together.
it is actually normal for helmutii to be taller (but not too much), this is a specific shape of theirs. i have another helmutii plant that is a troublemaker and understand your worries :)my collection isn't big at all, Heather. around 120 plants plus many tiny seedlings. i grow them all at home, no greenhouse or anything.thanks :)