
Perhaps the groomer did get a litle water in the ear ( very naughty ) as you say he is tilting his head to the side as if there is something in the ear or it could be caused by groomer cleaning the ears and going deeper than she should have . Sometimes although if the ear was a wee bit inflamed before (you may not have noticed ) and it was cleaned it might have irritated it more.
Did you ask the groomer if the ear seemed dirty when it was cleaned ? if it was there might have been just the start if a wee sore ear there as is quite common in long eared dogs.If I clean a dogs ears and I feel they are over dirty ( brown or black yuck on cotton ball ) I will advise my customer and tell them to watch out incase the dog has a sore ear starting.
If you are worried talk to the groomer to see what she has to say ( i.e. if ear was dirty and also visit your vet and they will have a look and give you someting if needed to sort out the problem