Hubby traveling with opposite sex co-worker"

Should I worry of my hubby who is traveling with a co worker who is a girl.? She is not his boss, just someone who needs to go and sign off on stuff and he's there for the muscle work. I ask him questions about the trip (not being pushy) and he told me stuff. But my brother comes and he asks him about it and he tells him a lot more. Like he has to pay for the hotel and his job will reimburse later, but we are short on money?? Am I overreacting.