"The best-performing sector year to date relative to the S&P is health care by a long shot," he added, also noting that utilities and consumer staples – all traditionally defensive plays – were among the top five sectors.
"That's not necessarily what you want to see at new all-time highs, so I think it'll be critical that technology gets off the mat and that we see some kind of input here from materials to the upside," he said. "We need that rotation intrasector to happen for bulls to feel truly comfortable that something bigger is at play than just kissing that historic high."
Stephen Weiss of Short Hills Capital said that the second quarter would see more uncertainty because of of Europe.
Although economic data from Germany was positive, China could have a slowing effect on the stock market, he added, possibly to the tune of a pullback of a couple of percentage points.
Weiss also noted that the utilities ETF hit an all-time high Thursday.
"That's not typical of a bull market," he added.
Shelter Harbor Capital's Brian Kelly saw fundamental reasons for a bear case, calling out Accenture's weak quarterly earnings.
"They can't blame that on Oracle salespeople," he added, alluding to that company's explanation for an earnings miss.
Kelly said that he had been surprised by the rally for a few months.
"The most frustrating thing about this market for people like me is that it's not necessarily responding to the economic data," he said. "We saw GDP, which was weak, this morning."
Trader disclosure: On March 28, 2013, the following stocks and commodities mentioned or intended to be mentioned on CNBC's "Fast Money" were owned by the "Fast Money" traders: Stephanie Link is long AAPL; Stephanie Link is long GS; Stephanie Link is long CSCO; Stephanie Link is long FB; Stephanie Link is long IBM; Josh Brown is long AAPL; Josh Brown is long GDX; Josh Brown is long GLD; Josh Brown is long XLU; Josh Brown is long TLT; Josh Brown is long WMT; Josh Brown is long HES; Steve Weiss is long BBRY; Steve Weiss is long TBF; Steve Weiss is long LCC; Steve Weiss is short JCP; Brian Kelly is long TREASURIES; Brian Kelly is long GOLD; Brian Kelly is long SILVER; Brian Kelly is short COPPER; Brian Kelly is short S&P; Brian Kelly is short CAC; Brian Kelly is short DAX; Brian Kelly is short EUROSTOXX; Brian Kelly is short KOSPI.