These pics are from the day I brought them home from Lowes; (i only noticed the spots after i got home) I was thinking because of the shape of the spots there may be a chance that this isn't mildew but rather mineral residue from water droplets, it would seem plausible that Lowes staff would water their plants from above with a hose attachment.

If it is mildew, though, what should I best do about it? I'm seeing a lot of different ideas for spray solutions and not sure which would be most effective

These were taken a few weeks ago and the plants have shown no other signs of ill health since

Cat palm and parlor palm