Could i have mono if kissing someone else with it?

Yes: Mono is often referred to as the "kissing disease". Like any other infection, if you expose yourself to someone who has one, you run the risk of catching it yourself.

Confusing question: At a listed age of 42, it is likely you had mono in childhood and are immune. If have never had it, you could get it through the saliva of an infected person but it would likely take several weeks before you developed symptoms.You don't experience it immediately nor would you pass it back & forth like strep throat.