5 Stories You May Have Missed This Weekend

— -- 1. Joe Biden 'Not Saying No' to Potential Presidential Run

Vice President Joe Biden's political operation has entered a more active phase in recent days, with several moves being contemplated to clear the way for him to run for president should he choose to do so, two longtime Biden advisers tell ABC News.

The vice president himself has not authorized any specific moves, but nor has he objected, a signal Biden confidantes take as suggesting he's serious about potentially challenging Hillary Clinton for the Democratic nomination.

"He's not saying no," one adviser said. "This is his time to figure it out."

2. Rick Santorum Says GOP Debate Rules 'Arbitrary'

Republican presidential candidate Rick Santorum said Sunday that the criteria for the first Republican debate this week, which will limit participation to the Top 10 GOP candidates according to recent national polls, are "arbitrary."

"These national polls are irrelevant," Santorum, a former senator from Pennsylvania who ran for president in 2012, said on ABC's "This Week." "I was at 1 percent in the national polls four years ago and ended up winning 11 states, 4 million votes, won the Iowa caucus."

3. FBI Investigating Small Explosions at 2 Las Cruces, New Mexico Churches

Two small explosions at a pair of Las Cruces, New Mexico, churches this morning have prompted an investigation by the FBI and several other law enforcement agencies.

No injuries were reported in either explosion, a Public Information Officer with the Las Cruces Police Department told ABC News.

The first explosion was reported shortly after 8 a.m. at a mailbox near an entrance to the Calvary Baptist Church, the Las Cruces police reported. Some people were inside the church at the time, but services had not yet begun, police said. The second came 30 minutes later, when an explosive device detonated in a trash bin outside the Holy Cross Catholic Church.

4. Watch Military Dad Surprise Son at Baseball Game After 6 Months in Kuwait

After six months in Kuwait, a military dad pulled off a home-run homecoming surprise at his son's baseball game in Illinois.

Joe Amore came back from an Air Force deployment two weeks before his son, Anthony, was expecting him, according to ABC's station WLS-TV in Chicago.

"I kept telling him middle of August," Amore told ABC News today.

So when Anthony, 8, was prepping for his baseball game Friday night, he had no idea his dad was already at the field, disguised as the catcher.

5. New ‘Ghostbusters’ Cast Visits Patients at Boston Hospital

Lucky patients at Boston's Tufts Medical Center were greeted Saturday by some special visitors dressed in jump suits and carrying special "Ghostbusting" gear.

ABC affiliate WCVB reports that the cast of the new "Ghostbusters" reboot –- Melissa McCarthy, Kristen Wiig, Kate McKinnon, and Leslie Jones -- stopped by the hospital in their costumes to visit patients.