I've also had my FPOV height get stuck in the "sneak crouch" setting a couple times. Moving to a new location (fast travel, certain doors) always fixed it. (I'm on a PC, and actually have a modded skeleton that makes my FPOV match my character's height; he's 1.3 times taller than normal. This has no effect on the bug except to make it rather obvious when it comes up, since I'm suddenly not looking down at everybody, ducking to get through low tunnels, etc.)
I often get stuck in sneak height, have no sneak related mods, I guess it happens if you do some actions like mining while in sneak mode, entering and exiting sneak mode solves it.
Another weird bug is if you zoom out from 1st to 3rd person view as an Khajiit your tail stand straight out, putting away weapons and take them out again solves this.