I would be very, very careful how I tred here if I were you. If there is nothing going on here the aligations of sexual misconduct could be devestating to both the child and her father. Honestly, I would take my daughter to school a couple of more times at least and watch what was going on between that girl and her father before I would say anything to anyone. I guess I'm saying I would make sure I'm seeing what I believe I'm seeing before I went any further. I know that my dd kisses her father on the lips everytime she says goodbye to him. Now the kisses don't last 7 seconds, not even 3 seconds and that obviously would make a huge difference. As far as the two kisses, I could easily see my dd doing that when her dad has just done something that she is extreemly pleased about. She will come back and thank us over and over for things when she is excited about what we've given her (permission to do something she thought we'd say no to has to top the list)
I hope you understand that I'm not saying to do nothing, I'm saying be very clear on what you are seeing before proceding further.