I wanted to try and make eyes, nose etc. for my character, so I went into edit mode and started changing the head of the mesh:
After making a few changes, I went back into object mode and saw this:
I suspect it has something to do with Shape Keys, but I'm still a newbie so I'm really not sure. I had "Basis" selected in Shape Keys while making the changes, but I'm not sure that's correct. What's happening and how do I fix it? Thanks.
Edit: I was following the steps of the accepted answer of this post:
Turns out it was the Knife Tool that caused my problem. I made a cut which didn't connect to a vertex, which apparently is a no-go. I still have no idea why my Shape Keys are affecting the the new vertices that I created on the face.