probably you have been flagged up for extra security - you can be selected for this randomly on US-bound flights - you have to collect your BP in person at the airport, and you will often/normally see the letters "SSSS" marked on the BP...which means that at the gate you get pulled aside just before the jet-bridge for an extra security scan

most likely that's what this is (assuming your ESTA is in date and no issue there?)

it's nothing at all to worry about, though recommend you don't take too much carry-on luggage (or give it to your husband at the gate before you get flagged up) as the extra security sweep can take longer if there's a large carry-on involved

nothing to worry about though - I have had this several times and never a real issue