Is it okay if Mom comes?

Here is a linguistic phenomenon that had me really confused the other day: sometimes, people will refer to their spouse in conversation as Mom or Dad (お母さん、パパ etc). Occasionally, this is very confusing, because I am not actually sure if whomever I'm talking to is referring to their wife or their mother. I'm sure you can see the Oedipal places this is going. Most of the time, people will backtrack and say, And by Papa I mean my husband, but the other day this was not the case, and I was introduced to a woman I thought was this man's mom, but was actually (probably) his wife. I did think she looked rather young for a mother of a man who is 40-50 years old. It was only later when she sent me an email in English referring to my acquaintance as her husband that I started to put the pieces back together. Normally I would have been more observant, but this guy (one of the people in charge of me from the co-op) I know does not wear a wedding ring and had talked about his mom before, who was actually his mom and not his wife. I'm pretty sure I have his relations sorted out, but it made for one heck of a head trip along the way.