(Evan Vucci/AP Photo)

ABC News' Michael Falcone and Emily Friedman report:

WEATHERLY, Pa. - Everyone knows Mitt Romney loves a good prank, and the presumptive Republican nominee took a moment on Saturday to gently tease the reporters covering his swing state bus tour.

In a hand-scrawled note penned by Romney, himself, and taped near the entrance of the bus carrying the traveling press corps, Romney wrote:

"You guys have it way too soft - nice ride.

Mitt

P.S. - Erased your hard drives - "

(Here's a photo of the note, tweeted by Associated Press photographer Evan Vucci: http://instagr.am/p/L7_QgnTbav/ )

Romney was ribbing the press for the plush limo-bus (complete with black leather seats, faux hardwood floors and flat-screen monitors) the campaign rented to ferry journalists more than 130 miles around Pennsylvania on Saturday.

But whether Romney realized it or not, the quip at the end of the note - "erased your hard drives" - provided an awkward reminder of a 2011 Boston Globe investigation revealing that before Romney left office as governor of Massachusetts in late 2006, "11 of his top aides purchased their state-issued computer hard drives, and the Romney administration's e-mails were all wiped from a server."

"Romney administration officials had the remaining computers in the governor's office replaced just before Governor Deval Patrick's staff showed up to take power in January 2007," the Globe's Michael Levenson and Matt Viser reported in a Nov. 2011 article.

(At the time Romney campaign spokeswoman Andrea Saul said in a statement that "the governor's staff complied with the law and longtime executive branch practice. Some employees exercised the option to purchase computer equipment when they left. They did so openly with personal checks.)

But a spokesman for the Obama campaign said on Saurday that Romney's attempt at campaign trail humor was no laughing matter.

"Mitt Romney may joke about how his staff erased government hard drives to keep his records secret, but what we do know about his record as Governor is anything but funny - he left the state 47th in job creation and number one in per capita debt in the nation," Obama spokesman Danny Kanner said in a statement.

But Romney's joke was just that - none of the press's hard drives were harmed, of course. In fact, Romney snuck onto the bus while reporters were still typing away on their laptops inside the Weatherly, Pa. foundry and machine shop where he held his first event of the day.