Yeah..totally agree, I would feel bad too but really shouldn't! Like another said I would totally feel the other parents pain in not being able to reach their dd.
One time my dd was about 16 at the time and she and her friend who lived around the block wanted to go to the basketball game at the high school. I drove the girls up there. Before we left, and in front of me, the other girl called her mom to see if it was o.k. she go, that I take her etc. She hung up said she could go. About 20/30 minutes later I hear a knock. This mom reamed me up one side and down the other. Evidently her dd was talking to SOMEONE else and not her mother. This lady let me have it for putting her dd in my car and basically accused me of kidnapping. I could't get a word in edgewise. I was so mad at the dd. But, turns out mom went to the high school and after what I got at the door I believe 100% her dd was mortified with the experience she had at the high school in front of her friends. I never took that kid in my car ever again. I learned my lesson.
Basically in the end teens cans be forgetful, sometimes deceitful and sometimes I think parents just go overboard in wanting to be in control of every move. I don't slam them for it. I understand where the mom/dad was coming from in your situation. But, at the same time I wonder why they panicked so quickly?? And why didn't the bus driver say oh yeah I got the note or oh yeah she was on my bus?
Kelly