Hey how is your good mood today?

Ok guys, after the depressing previous post, some lively stuff to report. One out of the two of my best friends, the Delhi one, is now a days in a perpetual good mood. Whnever you ask her how she is, she starts gushing about how good she is, how good life is etc etc. I took it one day, two days, a week, a month and eventually I felt suspicious. Well enormously so. What is all about this continous good mood? I kept asking her, I am dead sure she is seeing some man and not fessing up. I am even sure that the man is married hence the silence. It is pretty disconcerting to see someone in a perpetual good mood. I mean we are so used to being up and down and sometimes up for a long time and down for a longer time, that suddenly when your friend stays up all the time it gets to you. It sure gets to me. I mean come on, we all have problems in life, how come she is so super cheerful. I know she leads an immensely stressful life juggling full time Ph.D with full time work. Then I scold myself saying that I have become overly critical, here one of my best friends has found the fountain of good mood and all I am doing is being suspicious. If it was someone else, I would have been deadsure that she/ he is on drugs. But this girl and drugs or external stimulants just do not go together.
The standard dailouge between us now a days is, I ask her "hey how is your good mood today?" to which she repiles "hey my good mood is good today!".
Now tell me in today's stress is such a thing believable? Or am I the cynic here? Just because I cannot do this, I am suspicious of her as well.