Do age gaps really work?

my mate has been single for several years after a really messy breakup, she has now met someone at work and seems to have got herself all worked up bout it cause she really likes him and him her, he has asked her out for a drink but she is reluctant as hes 15 years older than her, i am so happy she has met someone and advised her to go for it, she deserves to be happy after all the heartache, personally i think age dont come into it neither have any ties or commitments, i just wondered have i done the right thing encouraging her and do you all agree with me that age souldnt matter!!!!!!!!!!!