Extrude issue
 

When extruding, i sometimes get the problem circled in the attached image. Doesn't always happen, just occasionaly. Any idea what the cause is?

That's ok, just noticed i had multiple vertices on top of each other, merging them fixed it. Not sure why i keep getting the multiple vertices though.

Extrude is a bit quirky sometimes. Happens to me atleast once per model. Worse is when you get edges that act up and you cant convert to subd's.

I think i have the problem when i'm extrusing edges then using the split poly tool and starting on a vertex. I need to be more careful in the future when doing this and check i'm not creating them on top of each other. I don't really use Sub D's so i don't know much about your issue.