New hire drug screen?

Hey all - I've received an offer and was wondering if I can expect a pee test. I should be clean by the time I start, but I just spent a week in oregon sampling the awesome legal weed they have and want to know if I should expect ibm to piss test me. I'm based on the east coast, so attitudes about weed are a bit different here than out west and it's bullshit.

Edit: thanks for the responses, lots of different and somewhat conflicting answers. Just an fyi - I ended up getting some of those home test strips to test myself and they came up negative (also it's not easy for a girl to pee into a cup, never tried it before). As for the legal points raised - I get it, weed is against federal law and IBM has contracts etc. but come on, it's weed. Blow and heroin junkies can pass a piss test within a few days but the occasional weed smoker gets punished for smoking a bowl a few weeks ago.