Listening for the compressor constantly running will give you a clue as to whether the strut is leaking. I doubt both have gone at the same time though. A height sensor failing can cause it to bottom like that, you need to get it up in the air to check it out. The sensors can be taken apart, cleaned and refitted if you're careful. Remember the struts have an outer rubber cover, this cover has a split in it from new so that's not an indication of the air bag having blown.
Should you need to replace them don't be put off by horror stories of how difficult it is, it isn't. I replaced all four on mine with new Arnott struts from the US, total with shipping 2.4k!