Steam under engine on a rainy day

[MerckMix]

Hi all,

Today I went for a drive in my 03 Outback H6 3.0 (95K miles); the drive was a couple of miles so by the time I arrived at my destination the engine was nice and warm (about halfway on the temp gauge). When I got out of the car I noticed, for the first time, that there was steam playing about the underside of the engine/under the driver's seat area. Nothing coming out from under the hood. The car tends to warm up pretty quick but has never overheated; checked the oil and it wasn't milky, and the coolant, albeit low, looked fine too (I topped the coolant off just in case).

Now it was in the upper 30s and raining pretty hard, so I'm wondering if the steam could have been caused by the water from the road splashing up off hot areas of the engine? I'm asking because I'm supposed to be doing a lot of driving over the next week and I'm trying to decide if I want to shell out the cash to have a pressure test done tomorrow to make sure the head gasket is sound.

Any thoughts? First time in ten years I've actually owned a car, so I can't for the life of me remember if my other cars would do this.

Thanks in advance!