In every version of KiCad, I've had wandering grid problems that show up randomly. This includes all the 4.X versions of the stable release; although I have not tested the last 2 stable releases).
I have, over time, found that pressing F9 then F11 resets quite a few problems.
For grins, I repeatadly hit F9,F11,F9,F11,F9,F11... repeat. What I saw on the screen was quite interesting.
OpenGL Rendering set to Subpixel Antialiasing (High Quality).
Full screen cursor checked.
Always display cursor checked.
Version: (2017-09-08 revision 19ad350c1)-makepkg, release build
libcurl/7.54.1 OpenSSL/1.0.2l zlib/1.2.11 libssh2/1.8.0 nghttp2/1.23.1 librtmp/2.3
Platform: Windows 7 (build 7601, Service Pack 1), 64-bit edition, 64 bit, Little endian, wxMSW
wxWidgets: 3.0.3 (wchar_t,wx containers,compatible with 2.8)
Compiler: GCC 7.1.0 with C++ ABI 1011
And, to make it even more interesting, do it a second time...
I'll try to do a little more testing to have a more polished report of exactly what is happening. I hope other users will report their results as well.