So what?
The premium was a relatively modest amount that you were paying out, No need to query it - or if there was it would be at the insurance company's end.
The insurance company cheque is for a sizeable amount, presumably. Under the money laundering regulations they HAVE to investigate deposits over a certain amount, or for any amount if they are suspicious of the source. You getting uptight about it will probably cause them suspicion if they didn't have it in the first place.