"I'M 28 YEARS OLD."

Chelsea Clinton repeated it so often at Villanova University yesterday that she evoked a laugh when she said: "I seem to be hung up on that today."

Me, too.

Because Chelsea's age and yesterday's campaign appearance - the 100th she's made in recent months - raise an issue I find irksome:

Her refusal to talk with reporters.

Chelsea has long since evolved from the little girl off-limits to the media because she was thrust into public life by her parents.

She's a grown-up now, and she's chosen to make herself a public figure, but still expects to be afforded the privileges of private life.

Chelsea's ban on talking with reporters has been enforced to the point of silliness.

In Iowa, she famously brushed off a fourth-grader reporting for the Scholastic News, saying, "I don't talk to the press and that applies to you, even though I think you're cute."

And Daily Pennsylvanian reporter Emily Schultheis, who attempted to question Chelsea after an appearance at Penn last month, told me she had been stopped by a campaign aide.

"I figured I was considerably less cute than a 9-year-girl, so I had no chance," she said. "But I thought I'd try."

Certainly Chelsea isn't afraid of tough questions: She's been asked more than once about Monica Lewinsky, and has learned to handle such rude inquiries with poise.

"It's very hard to give her a question she can't answer," actress America Ferrara, who has campaigned with Chelsea, told Newsweek.

Reporters honorably adhered to the unwritten rule to respect Chelsea's privacy when she was a kid in the White House.

But there's no justification for the unwritten rule she has now imposed.

When Sen. Clinton spoke to the Daily News editorial board last month, I asked her why Chelsea won't talk with the media.

"She is there in a supportive capacity for me and it's not about her," Clinton said. "And she doesn't want to make it about her.

"She really wants to draw that line and I respect it."

Well, Chelsea is all grown up now. And if she's going to be on the campaign trail, she ought to be subject to the same rules as everyone else.

This isn't coming from a Hillary basher by any means. I cling to the Clinton raft even as the Obama floodwaters sweep my friends away.

I agreed when Chelsea told students yesterday that her mother's misstatement about landing in Bosnia under sniper fire was simply that, an innocuous lapse from a sleep-deprived candidate. If Clinton was going to tell a deliberate lie, why do it about an incident with so much documentation, including her own?

I agreed when Chelsea said that the controversy over the anecdote her mother told about the pregnant woman who died for want of health insurance - which is or isn't true, depending on who's talking - is beside the point. The real point, she said, is the need for universal health insurance.

So this isn't just another opportunity to skewer Hillary Clinton, the most defamed public official ever.

But it is about Chelsea's sense of entitlement, about feeling empowered to live by different rules, and to have it both ways.

Her parents need to tell her the facts of political life, not continue to protect her from the mad dogs of the press.

Chelsea stood there yesterday, holding the microphone in one hand, gesturing with the other, articulating the intricacies of issues at length like the brilliant policy wonk she is.

She was surrounded at the end by a group of well-wishers; Clinton's Philadelphia press person reminded me as I watched that she doesn't talk with the media.

Well, it's about time she did.

She is, after all, 28 years old. *

E-mail porterj@phillynews.com or call 215-854-5850. For recent columns: