Is this lag or a glitch?

This is a short one. I do not know if this was lag or a glitch but I decided to report anyway! So, as in my other report, I was far from the spawn in my new found location to build a house and as I was building the floor, which was wooden planks, 3 blocks wouldn't render for about 5 seconds until I placed the fourth. They still lit up when I hovered my cursor over them but it looked just like air. As with my other issue, I did search before reporting so it is not my fault if it is a duplicate issue.