Given the circumstances, once is an accident. Twice is a trend.

Hillary Clinton gets asked about the possibility of a ticket with Barack Obama with some regularity, and has, for many months now, ably dodged the questions. On Wednesday, she raised eyebrows, however, by straying from the script — asked on CBS about running with Obama, Clinton said, “That may be where this is headed, but of course we have to decide who is on the top of ticket. I think that the people of Ohio very clearly said that it should be me.”

It was possible that Clinton just spoke her mind without any real forethought. This strikes me as highly unlikely — Clinton is probably the most disciplined presidential candidate I’ve ever seen — but it was early in the morning and maybe she slipped.

Or maybe not.

Sen. Hillary Rodham Clinton on Friday again raised the possibility that she might run with rival Sen. Barack Obama on the same Democratic presidential ticket.

Speaking to voters in Mississippi, where Sen. Barack Obama is expected to do well in next week’s primary, Clinton said, “I’ve had people say, ‘Well I wish I could vote for both of you. Well, that might be possible some day. But first I need your vote on Tuesday.”

It is the second time this week that she has hinted at a joint ticket with the Illinois senator; he has not ruled it out but says it is premature to be having those discussions.

You’ll notice, of course, that Wednesday’s comment came in response to a specific question. This morning’s comment, if the AP report is accurate, was unprompted — meaning Clinton specifically wanted to raise this point for emphasis.