When the disk is new if you don't bed the brakes in properly they can warp quite easily. As long as they have not done too much mileage since you can straighten them out if they are not too bad, just get some heat in them and let them cool off before doing too much other braking. (motorway at 2am good for that)
As they are cheap standard disks probably best to replace them and try again, different if you've got £2000 Brembos but then if you had they should have been bedded in according to their recommendations
