you should mention it in a casual just to let you know way to your son, she is their daughter it is there's to deal with if you sound like your making any implications or make a big deal out of it to your son your DIL will possibly take offence to this as it will look like you are implying something against her parents. If you do as suggested you will know that you have at least made them aware of it but not interfered or caused upset.
Advice needed re possible extension to house
Petition to stop the EARLY RELEASE for PC Harpers killers



because someone else turned up and was chatting and then we went to do something else. There was nothing else that I could think of that had upset her! Contrary creatures, little girls!