Why is he playing me hot and cold

There's this guy who works at my local Starbucks.

I went there about 6months ago and when I had made my order he said I was well manned, I didn't think any thing of it so just said thanks.
About a month or 2 past and I went again one time and he said it again. I was bit shocked and didn't know how to respond so just said thank you again.

I though he was just being friendly as most of the staff there always ask me how I am when they serve me

But since he said that he's been staring at me, started off about 10secs every so often. But in past 2-3 month, when I've been going he seems to stare at me for about 30-50secs quite often. Then a few time his male workmates were there and he stared at me then turn to them and they said something to him and he answered back/laugh at the same time (Like they were teasing/paying him out about something), then he stared at me again, and they sort of stare as well.

I went there about a 1.5 weeks ago and he acted like he didn't know me/was just a normal customer.

I went there last Saturday night and he was really friendly talking to me and stared at me from time to time

I went their last nigh he was making the coffees with this other girl, the other girl spoke to me and ask how I was, and he completely ignored like he didn’t know me/didn’t exist.
It was really busy so he didn’t have time to stop and stare so I couldn’t work out if he was just having a bad day or just doesn’t like me any more

But about 30mins later this other girl came in, not sure if she was a friend of his or a regular customer, but she went up and he spoke to her and was really nice/friendly to. Don’t think it was his girlfriend as 30mins after that another girl came and he spoke to her and was really nice.

Why is he playing me hot and cold? Is he shy, as he seemed really confident around those other girls and his workmates?

I do like him just not sure if he likes me back

Hi, speaking from a guy who was really shy and worked in a bar/coffee house, its sounds like he's probably a bit shy too. The customer-server relationship is always a bit hard to judge, as you say they have to be nice, and can also have bad days! I think you might just have to bit the bullet and ask him out on a date (maybe not for coffee though :p)