She is on a scent. Watch for cats or other critters that could be getting in your yard leaving their scent. Ours do this when they smell something in the yard. Sometimes Sadie can stay on a scent for hours and sometimes all day if a really exciting scent. If I try to bring her in when she is hot on a scent, she will whine and cry and pace and beg to get back outside. Luckily we don't have this every day. Usually it happens a few times a week or less.
When they are on a wild scent trail in the mornings, I have to chase Sadie down and bring her inside. Pooh Bear is easy to catch. If it wasn't that exciting of a scent, they will be over it by lunch time when they are let back outside. If it was a real fresh exciting scent they could still want to run and bark and bay at the scent still at lunchtime. WE have had times when they still want to get outside and get back on the scent trail barking and baying even when we get back home from work.
Hopefully whatever critter you have visiting your yard will move on soon.