Is it alright to catch up with an ex every once in a while if you have a boyfriend?

I have an ex from about a year ago, and every 2/3 months or so, we have a "how are you doing" email. Nothing romantic, nothing ual, and certainly, just a friendly, light chat that my christian mother would approve of. My current boyfriend doesn't mind in the slightest. He trusts me completely. He has a girlfriend too who doesn't seem to mind. However, yesterday, I happened to mention to one of my friends, who was also very fond of my ex, that Richard (my ex) was moving to California during a conversation about another friend who was moving state. She was shocked, she said that communicating with my ex was a betrayal to my boyfriend and although he doesn't mind, it probably hurts him deep inside and I should ignore my ex from now on. Like I said, it's only once every 3 months or so - does she have a point? Or is she being unreasonable? I have NO feelings for my ex. I'm just a naturally friendly person.