At the end of April, Strands, a San Francisco company best known for its music recommendation engine and its $55 million of venture capital, announced that it had acquired the money management service, Expensr, under undisclosed terms. Within a month, a source tells us, Expensr’s founders moved on.

Expensr’s two founders, Reman Child and Shawn Gupta, had actually been at Strands for about six months, integrating Expensr’s service with Strands’ recommendation technology. The combined product, moneyStrands, uses your financial history to recommend products and services that people with similar spending profiles have liked. Child and Gupta had presented the product on stage at Finovate shortly after the acquisition was announced.

MoneyStrands is still in closed testing, and it is unusual for the founders of an acquired company to take off after such a brief period of time. In many cases, acquiring companies use stock options with a three-to-five year vesting schedule to prevent exactly this scenario from playing out. Since neither party would talk about the terms of the acquisition, we can only guess that it was a cash deal or that Child and Gupta did not have faith that their stock options would ever amount to much.

When we reached out to Strands to get its perspective, we were held at bay for two days before the company e-mailed this statement:

Our acquisition of Expensr was a great help in getting a smooth head start in moving toward our vision for moneyStrands. Reman and Shawn were with us for about six months, and during that time, they made valuable contributions thanks to their existing product and community insights. This knowledge transfer has been incorporated into moneyStrands, which Shawn and Reman themselves announced on stage at Finovate in April. We have been in private beta ever since and are hard at work perfecting the product. Shawn and Reman are entrepreneurs at heart, and now that moneyStrands is off to a good start, they’ve made the decision to move on to create another project of their own. We wish them well with their new endeavor.

Child and Gupta did not want to comment on the nature of this new endeavor and the two say that the technical integration of Expensr was relatively quick and mostly done by the time they left.

Along with moneyStrands, the company has applied its recommendation technology in a number of ways. The re-launched Strands.com aims to take on FriendFeed and promises to use its engine to filter out the noise. Read about the company’s vision for this product here and what Read/Write Web’s Marshall Kirkpatrick thinks about it here.