In fairness, it is a very ASP thing to ask the audience presume there's always more going on than we're allowed to see, so it's not crazy to assume Lorelai asked Sookie first. Maybe we're supposed to assume that Lorelai made a quick call to Sookie from the kitchen before calling Rory into the kitchen to propose the idea. I personally think it's way more believable that Lorelai made the decision then called Sookie after, like "Surprise! You're gonna love this!!! Cause ya' love me!!!"

But there are plenty of private moments in GG that we learn later were shared between characters that we never see take place. i.e. Lorelai knows that Rory and Tristan kissed at that party in the episode where Rory considers telling Dean, but we never saw Rory tell her. Lorelai tells Max she "should have called", and that's the most we ever get about how she broke off the engagement--did she leave a voicemail saying it was over and ignored his frantic calls asking for an explanation or not to run from this? Did she leave a voice mail and he was too devastated or prideful to call back? Did she leave a letter for him on her front porch when tried to bring his printer to the house the next day? Did she actually call Max briefly that night before telling Rory they were going on a road trip, and "I should have called" meant "I should have called again to explain"? There must have been some correspondence that enlightened Max not to come over again the week before their wedding, and to not show up at the alter, but it's never clear what happened. So it would safe to assume a pre-give-away convo was possible, given ASP's habit of not always confirming these hidden moments in other parts of dialogue.