"let go"

I got a dental hygiene job last summer that I really enjoyed, and thought that they really liked me. I was hired to work Tuesdays, but usually ended up worked a couple days a week, just as much as they needed me. I went on Maternity leave planning on coming back Tuesdays to begin with and I would kind of go from there. Last Tuesday was supposed to be my first full day back to work ( I started my Saturday half day at another office a few weeks ago), but the week before that my boss called me to see what my plans were. I told him I was planning on coming back on Tuesdays (which the office manager already new, and I assumed he did) and he proceeded to tell me that he needed someone to work more than that. He had a girl he new that was covering my maternity leave that was able to work more and he wanted to keep her. So I'm kind of bugged. I thought I got along really well in the office and really like him as a boss and the staff. I went into the office yesterday for a filling that I had already had scheduled before all of this happened. I asked one of the girls that works there how the other hygienist was working out. She said she didn't really know her, because she works Mon & Wed & the hygienist only works Tuesdays. So, it makes me think that he wanted her instead of me, not because of the work hours, because she doesn't seem to be working more?

My Saturday office is in Layton closer to home & to Erik's work, so it'll probably work out for the best, but I'm still kind of confused because I am pretty awesome ; ). And I wish he had let me know a little earlier because I had another job opportunity a month ago which I could have taken. This job will work out good though. I'm covering someone's maternity leave Wed & Fri's in the summer and then I'll just see from there.