Pippa Middleton & George Percy Share a Smooch
03/05/2012 AT 01:40 PM EST
The royal bridesmaid, 28, and the heir to the Duke of Northumberland were spotted smooching in front of Middleton's BMW last Thursday, after she waited for Percy in front of his house.
Once he darted outside, Percy exchanged a warm embrace with Middleton that lasted "for five minutes," according to an onlooker.
"They seemed inseparable," the source adds, explaining that the close-knit couple "eventually broke themselves away from one another and Pippa got back in her car and raced off."
And she continued racing Sunday, when she came in 412th place in the Vasaloppet – a 56-mile cross-country ski race.