When does being friendly become too friendly? 

I consider myself a very friendly person. I feel that I am approchable, and maybe sometimes that is a bad thing! It's one thing to be friendly to complete strangers but, sometimes perhaps I cross the line. I work in a deli so I deal with the public. I think it is always important to have a smile on because it creates an inviting atmosphere for costumers. Nothing wrong with that. But, I must admit sometimes I get a little too friendly with the "regulars". I don't find this to be a problem though. So the old men can get a little perverted? They're old, i'm going to let it slide. It's actually interesting how once a person reaches a certain age it becomes more acceptable for them to be innapropriate. Not in a super creepy way but, think of it this way: If an 80 year old man told you that if he was younger he would ask you out then that's kind if sweet. However, if a 40 year old man tells you the same thing then you think "Ew, that's weird". But anyways back to the point I think that it is really important for young girls to be careful. Sometimes being too friendly can be taken for granted and you can attract some weird people!
The reason I feel the need to bring this up is because of an experience I had today. There is a certain delivery man who comes in and delivers soda. Now, I got to know him from seeing him every week so when he would come in I would joke with him. I would sometimes yell out "Hey best friend!" or silly little things like that. The weird part is though that he started getting too friendly with it. Like he would make comments like "i'm going to come in on saturday just to see you". How does one even respond to that? "Oh, um...flattered?" Not really! More like "creepy, im gonna walk away now!" So one day I suppose we got into talking about birthdays and I mentioned mine was April 13th. Not kidding this had to be at least a couple of months ago. So today as i'm leaving he is pulling in. Somehow he sees me and honks and waves and tells me to wait for him. Now that's already pretty freaky. But, whatever I'll go with it. Then he comes up to me and says happy belated birthday! He remembered that it was last friday and he said he was thinking about me.  He also said that he came in and told somebody to make sure they told me that he said happy birthday. Then he asks what I did and how old I turned. I told him 19 and he kind of touched my chin to insinuate how young I was I guess? In my opinion this is really crossing the line. Am I right? I mean it made me feel quite uncomfortable. Then to make matters even worse I see him in the parking lot and he says to me "Oh, now I know what car you drive!" I'm sorry...WHAT. Dude, you just pretty much just announced that you're going to stalk me! Now I might be just a little paranoid about this but, I found the whole thing to be incredibley creepy. I can only blame myself for this though. I have to learn when it's appropriate to be overly friendly! Life lessons. But hopefully I can get this guy off my back!!