jlmphotos

I heard that the XT-1 is spec'd for a mean time to failure of 150K actuations.

I've yet to do a wet clean on my X-T1 sensor.  Normally, just a Giotto rocket blower takes care of it.  However, if you changed lenses at the shore, it could be some fine mist/sea spray got in there as it's being blown about by the wind.  I'm assuming you used F22 to test the cleanliness?  Unless you regularly shoot at that aperture, and the spots are just a few that can be seen when closed down that much, I wouldn't worry about it.  Unless the place you had the sensor cleaned before would do you a solid and clean it again for free.
Honestly I try NEVER to change lenses at the beach/sandy area.  No matter if there is no wind or not, there are still particles in the air.

Doubtful.  Sensor spots would show up when you stop down the aperture.  Normally, unless the sensor is pretty filthy they won't show up at wider apertures UNLESS you crank up the contrast in post.  At least that's been my experience.

Hey,  I use both my X-T1 with the 18-55, 35, Zeiss 12 and the 55-200 for landscapes, cityscapes, etc.  I love it.  I've printed up to 24 x 18" (so far) and the results are phenomenal and I AM A PIXEL PEEPER. LOL
 
I also shoot with the Nikon D800, but "most" of the time I use the X-T1 -- even for stock images.  I then process them in LR 5.0, though I've used both Iridient Developer, and Silkypix.  But LR 5.x has really improved the process.