Slabs pulling character in a direction

I had made a farm, using wooden slabs to cover the water as I have done since slabs were released, I noticed when harvesting or planting the lane closest to the slabs I would be dragged in its direction

What I expected to happen was...:
I expected no response from a slab

What actually happened was...:
I was draggged in the direction of placed slabs

Steps to Reproduce:
1. build a wheat farm 3 plots wide on each side, with water source blocks centered. 
2. Cover water with wooden slabs
3. try to stay on the lane closest to the centered water

4. observe the pull