One caveat with Romney's lead on this poll is that it finds Obama winning the black vote by only a 76/20 margin. That seems like an unrealistically low share of African American voters for Obama.
Obama led by 87/11 in the May polling, which took place from May 10 to 13. That was immediately after the North Carolina vote opposing gay marriage and Obama's subsequent endorsement of same. May 13 was a Sunday, but most May respondents would not have sat through a Sunday sermon listening to their minister inveigh against Obama.
The sample is small - 810 people for the June survey, with 22% black, which would be 178 people. If Obama's "true" support among blacks was 90%, the standard error for that size sample would be (approximately!) 2.2%, so a result of 76% is statistically significant.
That said, the way peeved people poll in June will probably be different from the way they vote in November. This current poll is more likely to be a harbinger of reduced black turnout than a dramatically reduced percentage for Obama.