What to do, what to do......
Bro..... let it ride for now but consider two things.
First, if they did come and see some gear, they would have to leave the premises and go and obtain one to be able to do a legal search and still have it hold up in a courtroom.
Second, consider it fortunate that they found nothing because if they did, they would most likely, depending on the amount found or seen, would have "reasonable cause" to monitor your residence 24/7 just to see the what interaction takes place at your home.
One thing that you could do is get trace on the call and see that it doesn't occur for a second time... that maybe an option for you.... here in Canada things are done just a tad different... the buggers make up laws to justify their actions of "search and seizure".... the catch phrase is "probable cause" it covers a bunch of bases for them as well as covering their assets.... if you know what I mean.
Maxmuscle66