I'm writing a scene in which two characters have a bit of a heated snog in a broom cupboard. Neither is intending to take it any further. What word or phrase would best fit this type of situation? I considered 'quickie' and checked its synonyms, but that noun is usually associated with sex and there's none of that in this particular interaction. Besides, I'm searching for something more formal, either euphemistic or honest, but definitely polite, as opposed to something vulgar and informal.
An example sentence would be: 'She fixed her hair and quickly smoothed the wrinkles from her dress to hide the evidence of their [insert word/phrase.]'