SSIS project under source control (TFS)

I have an SSIS package under vsonline source control. Every time I open a package, it gets automatically checked out as two properties of the package changes:

- DTS:VersionBuild
- DTS:VersionGUID

Any ideas on how to stop this occurring when I have not made any edits to the package?

Why do the above properties get changed? What causes them to update?

This is a problem in a team development situation where you have checkouts you do not want and have to undo the checkout, otherwise you are blocking other devs from accessing packages for modification.

Thanks