Probably nothing at all to do with what you talk about in the back at all! If you spoke to customers inappropriately, they would "counsel" you, explain to you that you should not discuss those subjects, talk that "freely" with customers, etc. You have not gotten anyone actually saying things (bosses aren't "shy" about telling us when we do something wrong! :-) so I do not think you should worry about that.

You may/may not get more days by performing well; that is not a one-to-one correlation as the number of people available (presumably most doing okay or they would not be working there) is also a factor and, how long you have been there (seniority) and how much you make (if you have 5 people making $12 an hour and 5 making $8, you might use 3-4 "beginners"/less experienced staff with only one or two senior ones to save some money) and how much you ask for are all in there too.