being served?

I sent a debt verification to the ca on my medical bill in Feb. I sent it certified and got my slip back - I have yet to get anything from them. I was thinking of sending a second request. Well this morning at 7:30am I get someone ringing the bell - so by the time I got myself together & looked out, there was a dark car parked kitty corner across the street - there was a guy knocking on doors directly across the street, and kitty corner to me, and a guy on my porch. He was not wearing any type of lettered uniform, but the car had dark tinted windows, antennae - looked official - so by the time I turned off my house alarm & opened the door (only a few seconds really) they were in the car & they sped off. Of course my first thought was that it was maybe a summons for my debt - and hubby thinks I am nuts. IS this how they would serve? and why didn't he leave a card or anything? And how would I find out if it was? How much time is usually between a summons & the court date? - cuz I am fighting this debt - it is incorrect and I was told I had no balance - now they want over $9000 (after almost 3 years with no bills or any kind of communication) Anyway, perhaps I am just being paranoid, but I want to find out if that is what it was. Although the people across the street lost their house & the guy that bought it is apparently shady, so it could have been for that - I am just scared tho. thanks for any help