Penalty not served during pitstop?

Hi all

I got a penalty for some corner cutting, hitting another driver and decided to pit. Add a few more seconds for speeding in the pitlane. 5 lap race in ‘Grand Prix’ mode.  Obviously race ruined, so I go and get some new tyre. And guess what, after 2.4 seconds I am on my way again. Why did I not have to serve my penalty? Instead, it got tagged on at the end.

cheers, P