As others have hinted, decide what the worse case scenario is if you get a flat. If it ain't too bad, then you can go without it. I personally would get one, but I don't know your route, how strict your work start time is, etc. Basically decide what your backup plan is (walk bike, put bike on a bus rack, call a spouse, call a co-worker, etc.) and if it isn't bad, don't worry about it.