Congrats! That will be a solid piece of your resume that you can leverage to the future. You could ask your prof if there is room in the research budget to get you a bus pass so you aren't losing money by volunteering. When my husband worked in a research lab one summer during undergrad, for money, the prof added in a bus pass each month from her budget. You can probably find your prof's research budget on the net. It's probably large. Prof may say no, but it shouldn't hurt to ask.

Keep a professional attitude; don't be like some people who gripe but don't use their minds to analyze the situation they are in and make better and creative choices. You've don't well by getting this really solid sounding position. You'll get to do more than clean glassware, right? If you start out cleaning glassware, pay attention and try to learn everyone's job by listening and watching, so you are ready to take over on the day they can't make it in. Then your learning curve at that moment will be much smaller.