[LunarBerry]

When my girl was spayed in Dec. Her front arm and belly actually grown really fast, where they shaved her, but she's a cotton coat and cottons tend to grow fairly fast or average like humans. If she's a silky coat her coat may not grow as fast, otherwise, it might be how well she eats. I know that in my case, my dogs eating the better premium stuff I switched them to made a huge difference. I mostly noted with my jacks, their coat quality changed, my yorkie not as much since she's always been on premium.
Might just consider any changes in her or her routine the month prior to the grooming and during. She might be missing certain nutrients or it might be a random thing. If anything you can also ask your vet when you next visit, as long as she's not showing any other signs to be concerned with it could probably wait till she gets her next checkup