I've confirmed now that this only happens on resume from suspend. I've spent the last 2 weeks always powering off my machine and I never get any disk errors. If I let the machine suspend however, I will get drive errors preventing boot. I can fix the errors with fsck but clearly something is wrong.
Drive is a Samsung SSD 840 Pro, latest firmware applied. Ubuntu 18.10 Mate. Full disk encryption, formatted ext4 with luks/lvm
I found one similar question, but no other info. Thanks in advance.