OPM wants to talk to me on the phone.

I've held a TS/SCI since 2015. A year ago I had to submit a new SF-86 and do a new polygraph for re-evaluation after having my clearance for 8 years. Everything seemed fine. Yesterday my security officer told me someone from OPM wants to talk to me on the phone and it may take up to an hour. He said he doesn't have details but, in his words, "this is not unusual, they probably want clarification on SF-86 answers". I've been anxious about it all weekend. Is this unusual? Or am I just overreacting?