Fleas?!

Today could have started off better. Samson's nails were long and unruly, he was a bit stinky, the last of his summer coat was shedding away, and after a few months of hot weather he had lots of dirt that needed removing. Plus, he seemed itchy and he is prone to dry skin, so we decided to schedule a fall appointment with the groomer (we average one good groomer visit per season, sometimes 2 in the Spring) so he'd be fresh as a daisy for fall.
Since my neighbor's dog was also in need of a good grooming we made a dual appointment and took them in this morning. Upon our arrival to pick the dogs up this afternoon the groomer informed us that BOTH dogs had fleas. I have no idea where they picked them up, Anna's cat is an indoor/outdoor cat and we'd recently spent an afternoon with all 3 pets together, but all of her pets are flea treated regularly.
Thankfully neither of us has yet to find a single flea in our houses but we're washing everything- bedding, blankets, towels, both Anna's cats (one of whom she says seemed to think she was trying to murder him) etc, and giving all the rooms with carpet a good vacuuming. Plus I picked up some flea treatment for Samson at the vet this afternoon.
Here's hoping this is a one-time thing...not what I pictured my Friday afternoon to look like :(