after washing my car this morning. i noticed my headlights like this.

is it the seals that have gone?

my car is booked into ford on tuesday. its still under warrenty so should this be fixed?

Definately looks like the seals have gone, as its a defect, and one you couldnt have caused, it should be covered under warranty, however, your car is 7 years old, and it really depends on what warranty you have, an extended warranty may only cover mechanical parts, and not stationary items... check the print of your warranty for further clarification!

ford was happy to replace my headlights no problem

Glad to hear it, a very positive resolution is always a pleasnant change!