Ablin is a bit more cautious with the S&P's average price-to-earnings ratio over 17. The P/E represents the price of a stock divided by its earnings per share, and that average is usually under 16.  "I'm worried about a bubble," he said. "The metrics we track suggest the market is anywhere between 10 and 15 percent overdone if you pull the Fed out of the equation."  The market has been flashing plenty of warning signs, and its selloff in the final hour Monday was not a surprise after the series of record-setting sessions last week. For instance, the defensive telecom sector was the best performer Monday, and commodities-driven materials and energy were among the biggest losers. Both sectors rely on global growth.  (Read more: After getting crushed, this sector could be golden)  "We're in this hot potato market right now, where momentum is driving it," said Peter Boockvar, chief market strategist at Lindsey Group.  The small cap Russell 2000, off 0.8 percent, and Nasdaq, were again diverging on the downside, a negative sign to some traders who look for growth and small cap sectors to lead the market. Both are up more than 30 percent this year, while the Dow is up 22 percent and the S&P 500 is up 26 percent.  "We're due for a rest here," Boockvar said. "There's no question about it, but the bull market doesn't end until interest rates move back to 3 percent. I'm getting more bearish here. Many things are lining up. I think this is the last phase of the bull market."  But analysts agree that it's unlikely the stock market would see a pullback of more than several percent until next year—possibly around the time that Congress refocuses on the budget and debt ceiling, or if the Fed signals it will begin to reduce its $85 billion-a-month bond-buying program.  "The market hasn't cared about a mediocre economy. it hasn't cared about slowing earnings. It hasn't cared about Syria. The only thing I look for to reverse it is when the Fed becomes a factor, or the bond market does it for them," Boockvar said.  Another red flag for stocks is that investors have also been taking on record amounts of margin debt. According to NYSE Euronext, margin levels, or the amount borrowed to purchase securities, climbed to a record $401 billion in September.  (Read more: Larry Summers and the never-ending bubble economy)  Barry Glassman, president and CIO of Glassman Wealth Services, says the individual investors he speaks with are concerned about the market's run.  "The biggest challenge that I'm hearing from clients, as well as prospective clients, is they don't know what to do with their cash," he said, adding that they see bonds and stocks as pricey. "They don't want to be the people who plow money into the market at all-time highs.  "They are going through what we call financial schizophrenia," Glassman said. "They're going to go through those kinds of challenges, and they're left sitting on the cash. No decision is their decision."  One strategy he's recommending is to put some cash into long/short equity funds.  "These are strategies that are going long stable, or value companies, and shorting the high fliers," Glassman said.  There are plenty in the camp who believe the market can go higher until the Fed removes some of its stimulus, but there are also investors and money managers who expect to continue chasing performance into the year-end, fearful of losing out on potential gains.  —By CNBC's Patti Domm. Follow here on Twitter @pattidomm.
The new records on the stock market are a sign that stocks are getting pricey but not necessarily of a big selloff anytime soon.