3 day shipping turned into a week after being shipped today, what gives?

Is the 3 day shipping just a "best case scenario" deal now? Before purchasing something from a small business the shipping was advertised to be 3 days by USPS and now after being shipped today the tracking label estimates the 15th.

It's a piece of equipment for my job so I'm a little bugged since I expected to have it by the end of this week (I work weekends)