Just started playing SMB, am on CH3 currently.  I've noticed a few times when I've beaten warp zones they don't appear beaten on the map.  Some portals turn red when they are beaten, but some just stay purple.  I don't understand.  Even when I look at the red ones there is no indication if they are beaten or not, other than being red. Are some warp zones just duds?

Red warp zones are for when you'll get a character for completion. Purple are just for fun (and two bandages). Correct, there is no indication of completion, but they will show if you've received bandages.

Yeah, 
They are two different kinds of warps. 
 
Would be really nice if you could tell if they were beaten, 
I know there is one I didn't beat, But I'm not sure which one anymore so I'm going to have to go through them all one by one trying to find one I don't remember

Not sure why you don't have a completion time listed for warp zones. Granted, you aren't shooting for a par time, but it'd be a nice indicator that you've completed level as all of the others have.

Anyone know how to get the first bandage in 3-5 and 3-7 respectively?