If you did not properly wash down & sanitize the stand, yes, there could have already been a mold colony and/or spores already on the stand and there may have been enough moisture in the atmosphere to encourage growth. The only way you can test for mold is with a mold test kit...OR...if you have a good magnifying glass laying around, you can look at this material to see what it looks like close-up.....
If you're not familiar with what mold spores may look like, simply do a google image search for "mold spore images" and the first popup will be a collection of different spore images that you can get an idea from.....there are thousands of molds, so trying to find yours (if it is mold) could be very time consuming.....