My wife reached out to her ex

Me (33M) and my wife (30F) have been married for one and a half years and we have a 6 month old son. Recently her ex who she dated some 7 years ago lost his grandma and she reached out to him to offer her condolences. This ex was her first love and they dated from high school until she was in her early 20s for roughly about 8 years. When we started dating she once made a remark that there's one ex you should be always worried about and that's him. She reached out to this ex on facebook and offered her condolences. When I found out she downplayed the situation and said she was close with the grandma and was merely offering her condolences. Is it ever okay to reach out to an ex for whatever reason?