I doubt there is any concern. Apple has a document that suggests running your watch under a water tap if the crown starts to stick. I don't think you could possibly sweat enough to cause damage to a watch that many people are swimming with (probably not a good idea but I've read people doing just that.)
BTW, unless you bought the new non-Series 2 watch in the last week, you don't actually have a Series 1 watch. I would think the appropriate name to avoid confusion would be original Apple Watch. The Series 1 is actually a new product with different internals than the original. But neither one is completely water resistant.