Phone number in hubby’s phone

A few years ago my hubby had an emotional relationship with someone several states away. It has been dealt with, moved on and he hasn’t talked to her. Recently I phone a contact number in his phone without a name and as I read the messages she said her name. They had spoke again after like 3 years since the incident. However it was very innocent how are you doing. She had gotten a new phone number. I didn’t like that they chatted even though they chatted once and left her last “hey” on read. Those messages were from like April. Nor did he delete them. But I’m curious as to why he saved her number and didn’t put in her name. I don’t know if this is even worth bringing up. Do I leave it alone? I lowkey deleted the messages and blocked her number anyways. Because you know. She doesn’t belong there. lol