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.
And the Blessed One addressed the bhikkhus, saying: "Behold now, bhikkhus, I exhort you: All compounded things are subject to vanish. Strive with earnestness!"