...if this has been covered already.

I was very impressed by my first papier-mache project. I had an interesting evening making the paste and bottling it, then I spent several hours the next day making a very nice bowl, using a 9" diameter glass/pyrex bowl as a mould and using alternate layers of newspaper and manilla envelopes. The first article I read, before I started, had suggested putting oil on the mould before putting the first layer of paper down. However, the article that described the bowl that I was making suggested using cling wrap, so I did. I then let it dry overnight. Then...errr....then came the problem. I don't seem to be able to get the bowl off the mould. The mould had a very insignificant external lip all around it and, during construction, I had, without thinking, pushed the paper under the bottom (top of the glass bowl, actually, but it was upside down) of the mould but I was able to pry that away. However, I just don't seem to be able to get the bowl off the mould. Will heat or cold work? Any ideas would be welcome.