What do you think

So it starts like this we go to church with another couple and there kids, my husbands daughter is close to there 13 yr old there good friends. My husband is over there allot but a couple of months ago I noticed he was giving allot of attention to there 13yr old aswell. Now not anything crazy but tickling which he does with our kids and just poking fun. So I told him that since she's 13 you should watch it cause it's a little in appropriate. Then one night while we are having Dinner my husbands daughter said that there daughter is always asking about my husband and for pics. I thought that is really weird so we talked and he said yes that is weird. So I just told him that when he goes over there he needs to really watch hisself. Well this morning I picked up his phone and they have been texted for 2days 😳😳😳. I was so mad the text where not content was not inappropriate but I feel like what is my 42 yr old husband texting a 13 yr old ........ I am mad ...... should I be ?!? I talked to the girls mom and it was very innocent I'm not mad at the girl I am mad at my husband. Any thoughts