What are you measuring from? Some of the ground could have heaved. This is the time of the year where the maximum heaving is showing up. We just had a section of a county road heave up about 3'for 300' length when the soil moisture went up. Heaving comes from ice lenses that develop in wet soils and very often soil around/under structures and roads is not uniform, especially in the top 1 to 4' of if there are veins of granular soil that can carry water to a point or away from a point.
Just a possibility that I have seen many times.
No, it's not heaving. Every single post that surrounds the 1 acre pasture is level and then the 3 posts that had snow drifts on top of them are noticeably lower.
I have a similar problem, but it appears that one post has heaved upward only about 1-2 inches. The association where I live is demanding that everyone level their fences (or I'm just being picked on). The fence is about 8 ft long and 4ft high. I tried to dig around the center post, which is just slightly high, water all around it and smash it down with a sledge hammer with no success. There is ~16in of concrete surrounding it, no idea how deep. I just want a simple fix before I move out. I do NOT want to remove the post, concrete, etc, but only to move it down slightly. Is it possible to submerge this post just a tiny bit without a huge hassle or big $$? Please help!