Small business owners were a little more optimistic during April but are generally still cautious.

That's the finding of a survey released Tuesday by the National Federation of Independent Business. The NFIB's Index of Small Business Optimism rose 2.6 points to 92.1 last month, erasing a drop of 1.3 during March. The index was compiled from the survey of 1,873 NFIB members.

The index has averaged 90.7 since the recession, reflecting concerns about the economy and the potential impact the health care law will have on small businesses when it's fully implemented Jan. 1. So the April gain doesn't reflect a big rebound in owners' sentiment.

Many owners are pessimistic because their sales are weak. More owners said sales fell during the first quarter than those who reported sales gains.

And many owners still expect business conditions in six months to be weaker than they are today — a sign that the pace of expansion and hiring at small businesses will remain slow. Four percent say this is a good time to expand, but that's unchanged from March.

The NFIB reported last week that owners picked up their hiring pace slightly during April, the fifth straight gain. The number planning to add jobs rose 6 points, but that gain brought only to a break-even point.