2G Groan and liquid noise when parking

[Lakermelon]

Changed the oil 3 days ago, filled the tank and came home today. Pulled handbrake, put it in reverse then killed the engine and engaged clutch. As/after clutch engaged there was a groaning sound followed by what sounded like a jug of liquid being opened. Checked under the car, no pools of liquid or any leaks, no smells inside or out. Sorry if this is in the wrong forum. Bought this car 2 months ago just want to make sure I can drive it to school tomorrow. Thanks.

Edit: it's a 99 gst if that helps