Iím not sure if youíre expecting a different answer this time but youíve got me again and mine hasnít changed.
They can usually right themselves but they tend to have more trouble in new environments and on sand. Itís probable they would get back over again eventually but no need to stress them out waiting for that if you happen to see it.
Is there a particular place they are falling off of, or a tank mate that is startling them frequently? How often is it happening? Is it always the same snail. If so it could be that particular snail is a little weak or has an injured foot or something causing it to have more trouble than usual.