If you watch the replay Mangum sticks around not to congratulate Balderee but to talk with Kurtz and you can see him point to himself as if to say "my bad". Kurtz was open for a second and I think Mangum was attempting trying to throw a jump ball to him but obviously didn't work out like he meant.

It is interesting to think that the two balls that slipped out of his hand that game ended up in a touchdown and an interception. Both could have easily been an interception.