Workplace Theft

I have worked in a restraunt for 6 months now, and the first 4 months all the employees were eating the stock, nothing major like a piece of fudge. The manager knew but just said stop eating. then an assistant manager started and caught me eating a piece of flake and i had a meeting where she took minutes. The main manager said he would talk to me later, no warning has been issued or anything and I was wondering how long he has to give me a warning or something before its to late because its been a week and no-ones said anything. the problem is I have other things to moan about like working hours and don't want him to be able to do me with theft from said time ago!!