This is anecdotal only.

My last 6 years was spent doing exactly what you are going to do, but for a Canadian company that paid me to travel to the US client and do that job. I had no issues whatsoever, as long as I had a copy of the the initial contract for the client in my travel documents if it was requested by US immigration. US and Canadian laws in this regard tend to mirror each other, so I think you will be fine coming here.

But, like I said, you'll need to double check.