recently my engine seems to brake more than before. Say when i go down a hill in fourth gear, where before i needed to brake a couple of times to hold the speed limit, i now do not have to brake. This has been going on since a incident accured where the car suddently felt really heavy, and i actually thought i had a flat tire or a locked brake. Pulled over to nearest gas station to check tire pressure and brakes, but all was ok. When i drove off the problem was gone, until i noticed that the car now brakes more on engine.. Anybody got a clue what this might be?

I had a 60k service three days ago, and asked the workshop to see if the could figure it out. They checked the brakes, and could not find any other issues either..