As already discussed here:
http://www.fsdreamteam.com/forum/index.php/topic,25568.msg168109.html#msg168109it's not an issue, it's made intentionally and it's even indicated on the release notes.
We SUSPECT the issue happened on some users because we added support for extra-long path names ( more than 260 characters ), which is required to support MSFS but, in order to enable support for this feature, a special registry settings must be enabled in Windows 10 which is automatically set by the MSFS installer but, a user that never installed MSFS and never bothered to remove this Dos-era limitation from Windows 10, would miss the setting, and our previous update didn't work, because it was generating an airport cache compliant with the extra-long path names naming conventions.
Regenerating the cache at each startup seems to have fixed this and, it also has the advantage that, if you have a 3rd party scenery with multiple AFCADs that can switch using external utilities ( like different runway wind configs, or SODE/non-SODE configs, static/non-static AI, etc. ), those changes will always automatically picked up by GSX, while before you had to remember to manually regenerate the cache to prevent "AFCAD not found" errors.
If you properly configure your antivirus to add folders that contains sceneries in the sim to the antivirus Exclusions, the cache regeneration shouldn't take more than a few seconds and, it's done in multi-threading so, it won't slow down the simulator startup in any case.
