Verified answer

He probably didn't get it from you BUT there have been cases were the person remained contagious for months after their recovery from mono, but not 3 years.

There is another thing called flare up's, that are very rare but could happen. After you have been over mono, you can get a flare up and become temporarily contagious. You will never know when you have a flare up because they don't cause symptoms.

Remember, flare ups are very rare but can happen. And you would not feel sick at all.

You can also get mono from drinking or eating after someone with mono. That is another possibility.

People can be contagious 6 weeks before they come down with mono. He could have got it somewhere else.

Mono is a virus that stays with you forever. It can come and go whenever your immune system is down or you feel run down or sick. It is very possible you did give it to him. Maybe you didn't realize you were having an episode of it because it wasn't that bad and then you passed it to him. Very possible because it never goes away.