Found a girls number in bf coat, How should I react?

been married for 24 yrs and unfortuantly my Ex did a number onme . However he never cheated on me because he was a drug addict when he took off I did always think he was but in actual realty I learned his cheat was the drug additiction. I have a new BF after 2 yrs and he made me feel like i was on a platform and he works these hrs from 1:00 in afternoon till 2:00am. Recently his company went live and he ahd to stay at a hotel because he worked 96 hrs.On weekends he is with me and has his 11 yr old son faithfully. In addition he came out of a 17 yrs marriage where his wife cheated on him. Of course he has changed alittle , he doesnt have to please me as much because we are past the dating stage and we live together. I was looking for a lighter last night and found a girls name and phne number and in his coat because we are always stealing each other lighters. Whenhe called to say nite I did ask him about the girls number telling him I set myself up onthat oneand his response was a chuckle and said , thats so so and from work. He even went to the extreme of sending me an email from her that was sent to him and others onthe commitee so he could prove that she worked there.However her number is lostedonthe bottom so why would he need it written down on a small piece of post it? I laughed it off and when he sent me the email , I responsed back to him that :FYI back at you , is this why you wear cologne". This was a private joke to him and guess what the email went to respond back to this whoever person was ..which is fine , it was an honest mistake but should I be concerned or over anylzing it?