Losing any fat is "cutting"
A banana with your post workout isn't going to hinder you too much until low BF. But honestly, if you don't feel you need it (if your shake fills you up), don't take it. The average banana is only about 100 calories, most of which is simple sugar. It will spike insulin, which in turn will tell your body to store and stop burning. Like I said, I don't do any simple sugar post workout when I'm cutting.