Stocks closed slightly lower on Monday as new worries around a U.S.-China trade agreement emerged.

The Dow Jones Industrial Average was down 29.23 points, or 0.1% to close at 26,787.36. The S&P 500 dipped 0.1% to 2,966.15. The Nasdaq Composite also slipped 0.1% to 8,048.65.

Monday's moves came after a surge for stocks in the previous session. The S&P 500 and Nasdaq both gained more than 1%. The Dow, meanwhile, rallied more than 300 points, or 1.2%.

CNBC learned through a source that China wants to have additional trade talks before signing what President Donald Trump characterized Friday as a "very substantial phase one deal." It is not clear if the additional talks will take place in Beijing or Washington, however. Bloomberg News first reported the news.

As part of phase one, China would buy between $40 billion and $50 billion in U.S. agricultural products. China also agreed to address intellectual-property concerns raised by the U.S. In return, the U.S. agreed to hold off on a tariff hike scheduled for this week.

"As many lingering questions remain, there is significant doubt this truce will hold through 2020," said Jason Pride, CIO of private wealth at Glenmede. "Likely, these issues will reappear in some form before the election, perhaps in the form of renewed tariff threats or actions targeting individual Chinese companies."