The URL is used to perform geo localisation which is required for some functionality in TWebGMaps. We have noticed that the API becomes unavailable from time to time, but unfortunately we have no control over this.
We'll have to investigate if a more reliable alternative is available or if this behavior can be avoided in the future.
The issue has been fixed and the update will be available with the next release of the TMS WebGMaps. However, there is currently no ETA available for the next release. If you urgently require the fix, please request an incremental source update via email.