In just the previous episode, Lorelai says she doesn't approve of Lane lying to her mother, and she wouldn't lie to Mrs. Kim. Now however, she is willing to lie to Mrs. Kim for the girls to go to a Bangles concert, and even goes so far as to call Lane stupid for telling her mother the truth about where they are going.
When the four girls find their seats at the theater and Louise says, "Yes, they are", you can see the boom mic next to the "hot guys"' heads.
When Lorelai is sitting with the sewing machine in her bedroom, just after Sookie sits on the bed, the boom mic can be seen above Lorelai's head.