I find whenever I rapidly switch weapons using my scroll wheel, I will get stuck somewhere in the middle with a weapon that I don't want and have to manually swap again.

This happens when swapping with they keys too in-between grenades, if you do it too fast.
I.E you'll have clicked "3" 3 times to go to your 3rd slot molly, but hell pull out the 2nd slot grenade.

You then end up having to go all the way around, hitting "3" another 3 times.