Without even looking it up, I'm going to guess 'Just Another Undercover Assignment' by Wendy.
Off to check and if I'm correct, I'll be back with a quote....
And I was right so here's the next quote:
Lois suddenly found herself in his arms, kissing and being kissed
by him. His kiss was exquisite, soft and gentle, yet somehow
powerful. She was completely absorbed in the kiss, oblivious to
the world around her. There was no past, no future-- only *now*.
She couldn't remember *ever* being this elated by a kiss. It
almost felt like their souls were combining and floating like
gossamer. Then there was a tiny bump and she withdrew from his
kiss in time to see them bump into the ceiling for a second time.
"Oh, my god! That was...that was *wonderful*!"
Clark looked dazed. "That's never happened before! I had no
idea...I'm sorry."
"Clark Kent, don't you *dare* apologize! That was the most
incredible kiss I have ever experienced! So don't you *dare*
spoil it by apologizing!"
