"I'm sure I speak for all members when I ask; What model? "
He has a 4410, per his profile.
I don't know why the bolts came loose, but I wouldn't worry too much. Just drop the loader off...get your loader manual (if you have one), and follow the procedure in the manual. If the holes had been slotted, then you may have had a concern for alignment of the loader.
I would replace the bolts though...
Do examine the female threads (if any) in the mounting holes.
After you get all of them torqued, follow the schedule in the loader manual to check and re torque as required