Are there secondary causes of sea level change?
Yes, there are lots of other factors. 

Factors affecting sea levels are no different from other natural processes: there is a large number of coupled, non-linear effects, operating on every time scale, and at every length scale, and across many orders of magnitude.

The Wikipedia page Current sea level rise lists many of the known processes. And I wrote a blog post, Scales of sea-level change, a couple of years ago with a long list, mostly drawn from Emery &amp; Aubrey (1991). Here's the table from it:



Reference
Emery, K &amp; D Aubrey (1991). Sea-Levels, Land Levels and Tide Gauges. Springer-Verlag, New York, 237p.