I wouldn't worry too much as it isn't that unusual on a 1st clean.
Reclean them and see how they come up.
Many people will say it is a waste of time, but when you clean customers for the 1st time i find it better to check them later after they have dried.
Getting the 1st clean right is important for your confidence and will keep the customer happy if you haven't done a good job.
The good news is that once they do come up clean with wfp, the chances are they will always come up good in the future.