restaurant etiquette question

[drunkandinlove]

Last week my boyfriend and I went to a Japanese restaurant.  Before ordering we asked if they had sake.  They said they would give us sake on the house and that in the future if we wanted beer or wine we should bring our own because they don't have a liquor license.  So they gave us a carafe of sake, which was awesome and I was really impressed and we left a big tip (but probably not as much as the carafe would have cost in any other restaurant).  So tonight we are planning to go back and I was thinking how great it would be to get another carafe of sake on the house.  But my boyfriend says it would be rude to ask for sake again because they aren't getting anything for it but it's probably costing them money and that we should just bring our own.  I don't think they give sake to everyone but only those who ask.  I think if they did it once then they are willing to give the sake on the house, and that we should take advantage of that.  My boyfriend says it would be rude and that we shouldn't take advantage of the restaurant by getting something that expensive for free just because we know that they have done it before.

What do you think - should we ask for sake again or just bring our own?

EDIT: Okay, I hear you, my boyfriend feels vindicated, and we will bring our own.  Thanks for helping me not be a jerk!