I had similar experiences.
One way to deal with the excitement is to, at the begining of the meditation session, to decide to abandon all unskilful desire for joyful experiences.
Another way is to keep practicing until these experiences become rotine and there's no more interrupting excitement.
He turns his mind away from those phenomena, and having done so, inclines his mind to the property of deathlessness: 'This is peace, this is exquisite — the resolution of all fabrications; the relinquishment of all acquisitions; the ending of craving; dispassion; cessation; Unbinding.'
(Jhana Sutta - Thanissaro Bhikkhu translation)