Did the cats go with you? If they did, treat them... If not, don't. Either way, you should wash everything you took in really hot water. Lavendar EO is supposed to repel fleas- and it does to a point. Orange EO is better, but dangerous around cats (though you could use it in the truck). The fleas will multiply in furniture, clothing, carpeting, and bedding around you-- not go directly for the cats if they came in on you!
You can check to see if you ARE infested. Tonight, put a pan of water in the floor (where you think the fleas are hanging out) and focus a couple of bright lamps on it. Turn out all the other lights and leave the lamps on all night. In the morning, check the pan of water for dead and swimming fleas *eck*
Good luck! We kept getting re-infested last year from our yard- they would just track in constantly (lovely Kentucky summer)